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99 Grand Cherokee Ltd with a wiring demon
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michaelmccoy
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Jul 30, 2012, 12:18 AM
Post #1 of 24
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99 Grand Cherokee Ltd with a wiring demon
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Howdy folks,
Knowing that there are others that have encountered wiring problems with their Jeeps, (and knowing that true geniuses sometimes read such blogs), I thought I'd share my problem to see if a saint is among us.
The stealerships would have their way with my wallet and I would like to hang onto both of my arms and legs.
I picked up a really sweet '99 Grand Cherokee Ltd with 113K on it.
And it's a real sweetheart -- remarkable shape, inside and out.
A voluntary repossession -- for obvious reasons.
It wont run. 4.7 equipped.
Here is the best way to describe my problem:
The engine spins over but wont start.
Fuel pump is working as are the injectors.
No current to the coil packs, (from the ASD -- automatic shut-down).
New cam and crank sensors.
No fuse, relay or breaker problems.
Also, these components don't work:
Power windows, sunroof, wipers and signals, (including emergency flashers).
The signals will work occasionally.
The interior lights remain on all the time and have to be shut off at the switch, (that controls dash illumination).
No odometer indication.
Everything else works fine. Power seats, locks, mirrors, blower, radio, brake and head lights, reverse lights, all running lights, horn and complete bulb check, (with key on).
It is equipped with SKIS, (sentry key immobilizer system), but the small symbol indicating the wrong key doesn't illuminate upon the key-on bulb check -- so it's unlikely that this is the problem. Also, it's the correct key that has been with the vehicle from new.
A heater core was recently installed which meant the dash had to be removed and replaced, (but it ran fine afterwards).
If someone were to point me in the right direction, I would be eternally grateful. In fact, using my PayPal, I'd compensate them generously, (I'm not kidding, and I place a high value on honor).
Best regards, and thanks for taking the time.
Mike McCoy
(This post was edited by michaelmccoy on Jul 30, 2012, 8:16 AM)
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Discretesignals
Ultimate Carjunky
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Jul 30, 2012, 9:29 AM
Post #3 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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Can you communicate with the ECM using a scan tool or code reader? Any trouble codes being stored?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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michaelmccoy
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Jul 30, 2012, 10:51 AM
Post #4 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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You make a good point, although the wire color for powering the coils is different from the one powering the injectors -- there's a split at the ASD. I need to check output voltage at the correct pin on the ASD relay, and if it's not there, check the crank and cam sensors for pulse -- even though they're both new.
This, after much studying and pondering.
Do you know if the output at the ASD, (for the coils/injectors), is supposed to be there without cranking -- with ignition switch on? Or does the PCM require a pulse from the crank/cam sensor(s) to activate the ASD?
Thanks so much for your reply.
When, (not if), I get this beast running, I'll dance around my yard and it'll be burgers and beers for all.
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michaelmccoy
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Jul 30, 2012, 11:15 AM
Post #5 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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I was told by the fellow that I bought it from that no codes were there.
Because the wipers, windows and sunroof don't work, (and the signals come and go), I likely have a compound problem that affects the OBD.
I borrowed a serious Snap-On scanner and have been told that during cranking, I should get an RPM reading.
This indicates an operational crank sensor, at the least.
My knowledge of scanners is scant, but I'm going to dive in head first.
I have little doubt that the lack of voltage at the coils is the sole reason for non-start/run -- so I'm starting there and going in reverse leading to the PCM.
By biggest fear is a defective PCM, those are pricey bastids -- not to mention the SKI issues with the chip in the key.
I've been told to get the correct key that goes with a used PCM that I might have to buy.
I have already bought a BCM on the advice of a friend -- $122 shipped -- but it made no difference, so I hate to make another expensive stab at it with a PCM replacement.
Thanks so much for your reply -- slowly but surely, I'm gonna crack this nut.
And support from other folks with common interests is really nice.
Best regards,
Mike
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 30, 2012, 11:43 AM
Post #6 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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OK, you need to back up and slow down here. First, you don't have to make separate replies to separate responses because we all see all posts.
You just need to go back an don your checking over again. I think you made a mistake in testing somewhere. If you have injector pulse and power, the ASD is working. You may even be checking the wrong wires. The wire for the power supply for the coil rail is DG/OR just like the injecors because it's coming from the same feed.It also power the fuel pump relay so we know it's working.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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michaelmccoy
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Jul 31, 2012, 2:01 AM
Post #7 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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OK, I haven't studied protocol -- I merely replied to each response as a matter of courtesy.
Two separate issues/comments by two separate people.
As to the power wires to the coils, they are DG/OR -- but the power wires to the injectors are DG/LG.
The same source pin for both at the ASD, (#87), but the DG/OR wire goes directly to the coils, whereas the LG/DG wire for the injectors goes through fuse #26 in the PDC first.
But you're right -- same circuit.
I thought I smelled gas upon cranking at one point, (as did an experienced mechanic that was visiting), so I assumed the injectors were working -- but I didn't get voltage at the coil wire(s), so the injectors must be without power too.
(Automotive electrical assumptions can be tricky, I know.)
I have a friend that will bring me a node to test the voltage and pulse at the crank and cam sensors. I understand the ASD won't activate without a signal being received by the PCM, (especially from the crank sensor).
I'm making a tricky assumption that the crank and cam sensors are good because they are new -- but it's best to confirm -- and I will.
Obviously, something is not allowing the ASD to activate, and I find that the fuel relay and pump don't rely on the ASD -- straight shot from the ignition switch to fuse 12 in the JB and to the relay via OR/DB. Then DG/BK wire from the relay goes right to the pump, which is grounded locally.
But again, the injectors and coils aren't getting 12 volts and the ASD has to be the cause. The crank sensor is my prime suspect until I can confirm.
Thanks so much for your input and advice. My quest and mission continues.
Best regards,
Mike
PS: Know any way I can post a pic of this sweetheart?
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michaelmccoy
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Aug 1, 2012, 1:01 AM
Post #9 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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Quote
You need to find out exactly what is working and what isn't before going any further.
Right, I suppose.
But I have to go farther in a process of elimination.
My friend brought all kinds of noids, but not the type to test a crank sensor.
Drat.
Here's a rundown:
The ASD is merely a relay, on or off, controlled by the PCM. (This, because the amperage drawn by the coils and injectors is too high to be managed solely by the PCM.)
The ASD allows positive current to the injectors and coils, (which are correctly fired/triggered on the negative by the PCM).
The PCM will only allow the ASD to engage if a crank sensor signal is being received -- during cranking and run.
With no voltage at the injectors or coils, it seems likely there is either no crank sensor pulse -- or the PCM has a problem.
The latter makes me nervous, because the PCM works only with the proper key -- because of the SKI system.
I can get a PCM with the matching key(s), the ignition lock mechanism and -- I'd have to get the door key mechanism too if I want to keep the key system uniform. (No key in passenger's door or liftgate.)
Also, I understand that a defective cam sensor won't prevent start-up -- but the engine will run poorly.
The crank sensor, however, is critical.
Do you know of an effective way to test/confirm the crank sensor operation/pulse with a digital voltmeter/ohm meter?
Finally, it seems likely that the lack of power windows, power sunroof, wipers and signals is in another area.
Naturally, that is for another day, as getting the engine running is mission #1.
Again, thanks so much for your advice -- two heads are really a lot better than one.
Best,
Mike
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nickwarner
Veteran
/ Moderator
Aug 1, 2012, 5:31 PM
Post #10 of 24
(2753 views)
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Re: 99 Grand Cherokee Ltd with a wiring demon
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There is no noid light that tests a crank sensor. They are for injectors. Your multimeter can test for 5v reference signal and continuity to ground and PCM but cannot capture the signal from that sensor. You would need an oscilliscope to do that.
We all are professional techs here. We do understand what relays do, how injectors work and how the PCM relates to all of this. I know some forums are a bunch of shadetree hacks but we do things a bit differently here. We don't allow those type to post and give bad information.
You really need to get this plugged into a tech level scan tool that can run ATM tests and show full datastreams. Nothing less is really going to cut it and throwing money at it only serves as a diet plan for your wallet with an expensive lawn ornament as a reward. You aren't going to know whats happening in this without that scanner.
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michaelmccoy
User
Aug 1, 2012, 11:44 PM
Post #11 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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Thanks Nick,
I have borrowed a nice Snap-On scanner with a wide assortment of adapters, (Solus Pro EESC316).
I'm told that I need to check the voltage at the diagnostic port to make sure the voltage isn't too high. (?)
This, to prevent damage to the scanner -- (although I am at a loss as to how the voltage could exceed that of the battery.)
I'm an old carburetor rebuilder from yesteryear, and I just need to drag myself into the realm of electronic engine management.
But I'm reluctant to just wing it without a measure of guidance from an experienced user.
Am I correct in assuming that if I get an RPM reading upon cranking, that the crank sensor is working correctly?
Thanks so much -- I really appreciate your advice.
Mike
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michaelmccoy
User
Aug 2, 2012, 11:41 AM
Post #13 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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Thanks Hammer,
-- for putting my fears to rest. The thought of frying that borrowed scanner could get into my nightmares, given that my friend volunteered it and it's darned pricey.
At around 4 grand to replace, it's likely valued at nearly as much as the Grand Cherokee itself.
And thanks for your patience with me. Unlike some folks that seem to feel that they were born with such technical know-how, (one friend in particular tends to look down his nose), I'm having to learn it the old fashioned way.
I am far from an expert and make no such claim.
I hope to get the scanner hooked up this evening, (with some guidance), and look/hope for some magic.
Best regards,
Mike
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nickwarner
Veteran
/ Moderator
Aug 2, 2012, 6:57 PM
Post #14 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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I also own the same scanner and am glad you have access to true quality tooling. It will make things much easier for all parties involved. I think you will need the K-17 personality key for that model, but the scanner will direct you itself. Chryslers used an auto-id feature that inputs VIN info after you input the tenth digit of the VIN and allow it to do so. Its actually a pretty user-friendly system to use and we can talk you through its proper use. You were right on with the cost, mine was four grand. Now it needs an update for another grand. Welcome to our world.
Like HT said, no way you can get higher than battery voltage at the ALDL port. Its impossible. If the same person who told you that nonsense gives you more advice, do yourself a favor and ignore them. They waste their breath and your time.
Looking forward to seeing what data comes up with the right tool in your hand.
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michaelmccoy
User
Aug 4, 2012, 4:12 AM
Post #15 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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NEWS FLASH!
Back in April, the Grand Cherokee was towed when it appeared to be abandoned. The owner said the signals stopped working, and she was afraid to drive it for fear of a ticket.
(I'll never know the whole story or details because everyone involved seems to be a spin doctor.)
The seller, (car lot), says it's all her fault and she says the same about him. The finance company was clueless and caught in the middle.
It seems likely that the towing company had an employee that wanted the GC real bad and for cheap. He took it upon himself to circumvent due process and had the Jeep taken to a salvage yard -- where a friend/cohort worked.
The plot thickens.
There were (shabby) records showing the GC had been crushed -- no kidding. The seller obtained papers that allowed him, (escorted by a Sheriff's Deputy), to inspect the property, where the Grand Cherokee was hidden behind a wall of junk. He repossessed it, reached his breaking point trying to get it running and offered it to me -- as a friend and knowing that I tend to be persistent -- (and knowing I love Grand Cherokees).
Now to the non-starting problem.
It seems someone in this process, (and with particular skill/know-how), bent a small male blade in the socket right behind the battery and next to the firewall. A single contact in a plug of about 15 - 20 wires and guess which one it was.
The very wire that carries 12 volts to the coil harness from the ASD.
Sabotage, pure and simple. And they knew what they were doing. Complete disable -- and easy fix.
The scanner was indicating everything was right -- the ASD, the crank sensor, the fuel pump and even the injectors could be fired independently. In fact, the scanner was finding nothing wrong.
So we started checking at the ASD. We found voltage coming out as designed, but not reaching the coil harness. By that time I knew we had the culprit cornered -- it had to be wiring or a connector/splice. My partner and I zeroed in on the plug and when he pulled it apart, the carefully bent blade jumped out at me. It was right in a corner of the plug, bent and mashed up against the plug wall.
We knew right away. With a careful straightening with needle-nosed pliers, he plugged it back it and, on the first spin, the Jeep came to life.
As promised, I danced around the back yard, and there will be burgers and beers for all comers tomorrow night!
The bulb check works perfect and all bulbs go out, no check engine, no ABS. The Jeep runs like a top, shifts, drives and handles like new. Very smooth and quiet with no bearing noises or shakes/wobbles.
With 113K, the Grand Cherokee is just getting broken in.
There is a minor exhaust leak rear of the cat/conv.
But I still don't have power windows, wipers, signals/emergency flashers or sunroof. The climate control is also dead as is the AC button. Blower and air controls work. The automatic head lights are also not working and there's no odometer display.
So my mission goes to chapter two -- but at least I know I have a solid vehicle with a fine running gear. More studying of the wiring layout to come, and I strongly suspect that the remaining problems are going to have a single, common cause -- the saboteur was an evil genius, so I have to think as he would.
Again, thanks so much for your advice and patience -- and for any that have been keeping an eye on the progress, more is surely to come.
Best regards and most sincerely,
Mike
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Tom Greenleaf
Ultimate Carjunky
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Aug 4, 2012, 7:04 AM
Post #16 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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Non mechanical but asking you if you have clean title to this thing? That's a scary history,
T
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michaelmccoy
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Aug 4, 2012, 10:25 AM
Post #17 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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The seller has followed due process to the tee -- including a court hearing where the buyer had a chance to explain why she apparently abandoned the vehicle when the signals stopped working. She also stopped making payments and when contacted by the seller, she surrendered the keys.
Following the hearing, the judge ruled the next day, and she lost. She also lost a sizable down payment -- although she was offered the chance to make full payment of the remaining balance, (about $3,400.)
She declined, (or was unable).
West Virginia law is brutally clear. Under such or similar circumstances, the purchaser continues to make payments while seeking a due-process remedy -- which begins with contacting the seller.
So, the title has been restored to the seller/lien holder through a properly executed cure, and I'm awaiting its arrival from the DMV.
It's unfortunate that the buyer experienced what she did -- it really is a shame. Her knowledge of the law is likely scant, but she really should have explored her options rather than simply leaving the vehicle, not contacting the seller and ceasing her payments.
When we were able to awake the Grand Cherokee from its 3 month slumber, I put a dealer plate on and stretched her legs -- and she is very much like a spirited race horse. Not designed to be in a stall, but made to run. I admit, I'm partial to Grand Cherokees, but she is an exceptional vehicle in every way -- and I couldn't be more pleased.
With this bit of a dark cloud on her history, I hope to improve her pedigree by giving her years of honorable service and much TLC.
Best,
Mike
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michaelmccoy
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Aug 8, 2012, 12:27 PM
Post #18 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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The Grand Cherokee runs absolutely perfect. It seems to actually keep itself in the center of the lane with shifting, steering, suspension, brakes as though it just came off of the showroom floor. No issues at all -- well, except the dead wipers, signals, sunroof and signals that come and go.
The illumination at the HVAC controls, overhead display, shifter and odometer is dead too. The more I study the wiring layout, the more I am convinced that there is a common source for the problem.
The signals/flashers come and go as before, and I think the problem here, is separate.
Ground, ground, ground.
I have a steak dinner wager with a friend, (families included), that it's all going to be traced to a grounding issue.
An old geezer I knew years ago in the service once told me, (with particular gravtas in his eyes and tone), that all automotive wiring problems should begin with a ground confirmation -- especially the simultaneous failure of multiple functions.
I can't count the times he first determined if the vehicle had had any panel replacements/collision repair. He would take a minute to check every body panel -- even the doors with an ohmmeter. Then he'd confirm the presence and contact at all ground straps -- and he solved many problems right there.
Get this: Last night, after poking around with some careful exporatory surgery, I inadvertently left the flasher button in the on position -- and today the flashers were blinking all around.
Weird, eh?
The signals had (magically) returned and I fired it up to charge the battery.
I always leave the wiper switch on too, to be aware if I poke it in the right place. No luck yet -- but I am confident that when the wipers come alive, so will the windows, sunroof and various lighting.
On another (yet related) matter:
A (different from above) friend of mine makes a wide variety of claims that qualify him for nearly superhero status. When I reveal the ground problem(s) with this Jeep, he'll provide some reason that he was wrong -- but his self-proclaimed genius rating will remain unaffected.
Most importantly, he claims to be a certified ASE mechanic.
He maintains that tires pressures should be set at the figure on the tire, showing max pressure. I know it's indicated on each vehicle's placard.
He didn't know that a Jeep's (Dana) live axles had a rubber filler plug in the covers.
He was not aware that the Jeep transfer case, (along with other makes), uses standard tranny fluid.
After using a scanner, he informed me that I should avoid a 2001 Maxima because it needed so many sensors and such, that it had a burned valve, (he withdrew the assessment later), that the ECM was bad, (nope, not that), and that the timing chain was worn out.
I bought it anyway and made about a grand on it after some detailing.
Turns out, two or three sockets were corroded, and the scanner was not getting the info correctly. The timing chain was well within limits and the sockets/connectors were cleaned/replaced. It now runs perfect.
He maintains that any vehicle should be ran hard (jackrabbit starts, routinely to the floor), in order to "keep it clean". That the (especially) engine, tranny, suspension, steering and brakes are "designed to take it. That even the electronics and sensors stay in better shape. That a comparison with a identical vehicle with the same mileage would reveal no difference -- or that the one that was ran hard will have a cleaner induction system and cleaner engine internals.
Comments?
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 8, 2012, 12:47 PM
Post #19 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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That guy's a real prize.............
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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nickwarner
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Aug 8, 2012, 1:33 PM
Post #20 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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No vehicle was made to take heavy full throttle abuse consistently. Jackrabbit starts put a lot of people in tow trucks. Any moving component will wear out eventually. The more stress exerted on them the faster this will happen. If you drive through gravel roads and cornfields a lot your suspension will wear out faster than driving easy down a new freeway. It is the nature of the beast.
Great job finding the fix and for posting it for us.
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michaelmccoy
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Aug 8, 2012, 7:45 PM
Post #21 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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Yes Hammer, he is. Some ego trips are amusing, and some are unsettling.
And I just offered but a few examples. He points out his legendary and exceptional skills repeatedly, and he's shameless in his blustering.
Don't get me wrong, he's a capable mechanic -- just sort of weak on diagnostics -- especially when he makes confident pronouncements, (which is a lot). Whenever he's wrong, his excuses are as impressive as his claims.
I'm hoping that he'll tire someday of basking in his glow -- but seriously, I'm doubtful.
Nick, I couldn't agree more. I liken a discussion about running a vehicle easy vs hard to using one sewing machine always on fine fabrics and a second identical machine mostly for heavy leather and denim. Or two identical lawn mowers -- one constantly used on heavy brush and uneven terrain, the other on golf greens.
On the Grand Cherokee wiring problems, I have a suspicion that the front end has been repaired at some point. The base coat is identical, but the clear looks a bit fresher/shinier in just the right light. There are three serious ground points at the top of the fenders, two on the passenger's side, one on the driver's. I'll start poking around at these points and move rearward. With another serious ground point under the driver's seat, I'll pierce the black wire that goes to it and ground it right to the battery -- all the wile listening for the wipers to move.
Again, I'm pretty sure the wipers awakening will also see the windows, sunroof and various illumination come alive.
All in all, I hope to learn more about the wiring problems that can befall a vehicle, and I am truly pleased to share my discoveries with you good folks. Thanks for your interest and advice, and
Best regards,
Mike
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nickwarner
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Aug 8, 2012, 8:24 PM
Post #22 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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another trick you can do to test ground is to voltage drop the ground circuit. Backpin the ground connector and hook your meter between it and battery ground, then try to energize it with the switch. Watch the reading. Anything over .3 indicates poor continuity to ground.
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michaelmccoy
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Aug 9, 2012, 3:42 AM
Post #23 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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Is there any advantage to that method, over just checking the ohms/continuity between two points using a standard ohmmeter/multimeter?
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Hammer Time
Ultimate Carjunky
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Aug 9, 2012, 4:03 AM
Post #24 of 24
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Re: 99 Grand Cherokee Ltd with a wiring demon
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Yes, definitely. It measures the amount of loss in the path.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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