|
|
Will computers give warning before dying in 95 Jeep?
|
|
|
| |
|
|
gruen
New User
Jun 22, 2006, 10:50 AM
Post #1 of 7
(1617 views)
|
|
Will computers give warning before dying in 95 Jeep?
|
Sign In
|
|
Would a computer in a 95 Jeep Grand Cherokee w 90K miles give any sort of warning before dying? I took my car in to get the a/c fixed--it was in perfect working order otherwise. The mechanic said I needed a new evaporator and hose assembly, and it was a very big job so it was almost $800. When I picked the car up, they had left the parking lights on and it didn't start immediately. When I got it going, it made a squeeling noise all the way home, then it started jumping and sputtering like a stick shift being stalled, but it's auto. I made it 1/2 way back to the shop and it died completely. Before the mech even looked at it, he said it wasn't his fault. Then he called and said the computer was shot, still not his fault, it it's going to be $600. Am I being ripped off, or can this really be coincidence? If I am being ripped off, what should I do? They have my car and it's immobile. Help!
|
|
| |
|
|
Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 22, 2006, 12:50 PM
Post #2 of 7
(1614 views)
|
|
Re: Will computers give warning before dying in 95 Jeep?
|
Sign In
|
|
I smell a fish here! It sure is possible to be a coincidnece and the evap in a Jeep can be tough and involved but I don't know how they knew what they thought was the problem now so fast?? This will be very hard to prove. Good luck, T
|
|
| |
|
|
DanD
Veteran
/ Moderator
Jun 22, 2006, 6:44 PM
Post #4 of 7
(1608 views)
|
|
Re: Will computers give warning before dying in 95 Jeep?
|
Sign In
|
|
I don’t want to make any form of judgement on this until I would hear both sides of this story.
First off there isn’t any one piece of diagnostic equipment that can see every different system of the vehicle. For the AC leak they probably used some form of refrigerant leak detector that would set off an alarm signal on the tester when the probe of this tester was close enough to a leak. In this case your evaporator who is a mechanical device not an electronic one. Meaning even if they used a scan tool connected to the computer it would have only told them that the AC system was low in refrigerant not the cause. At the same time the tech was only looking for an AC problem and probably didn’t do a full diagnostic scan. The vehicle was there for an AC problem.
What may have happened is while they were working on the vehicle they allowed the battery voltage to go down (due to doors being left open or they disconnected the battery) The point being that the engine management computer lost it’s adaptive settings due to lack of or no voltage.
Adaptive settings are things that the computer has learned (over time) to keep the vehicle running “normally”. Normally doesn’t mean as intended but what the computer has had to do to keep the vehicle running “normally”.
During this kind of repair so much of the dash has to come apart that the safest thing to do is disconnect the battery as to not cause an unintentional short to ground.
Disconnecting the battery will/could wipe out all of the computers adaptive measures and at times for whatever reason the computer will not implement them again.
Without being there to see and scan the system I would say this is a very unfortunate situation for both parties.
Dan
Canadian "EH"
|
|
| |
|
|
Guest
Anonymous Poster
Jun 23, 2006, 8:38 AM
Post #5 of 7
(1604 views)
|
|
Re: Will computers give warning before dying in 95 Jeep?
|
Sign In
|
|
Disconnecting the battery will/could wipe out all of the computers adaptive measures and at times for whatever reason the computer will not implement them again.
If this was the case, could the computer potentially be reprogrammed, or does it automatically need to be replaced?
|
|
| |
|
|
DanD
Veteran
/ Moderator
Jun 25, 2006, 6:07 AM
Post #6 of 7
(1602 views)
|
|
Re: Will computers give warning before dying in 95 Jeep?
|
Sign In
|
|
Yes in theory it should relearn adaptive strategies but that’s if the computer hasn’t lost its ability to.
This is just an example; the injectors over time become party plugged and cannot deliver the proper amount of fuel in a certain time frame. The computer is constantly receiving a lean indication from the O2 sensor and lengthens the injector pulse width (the injector on time) until the O2 starts toggling. The computer is happy and stores this adaptive measure in its memory. These adjustments may have taken months/years for the computer to tailor because the injectors didn’t plug-up over night.
Something happens to the computer and it cannot see or recognize that another long-term adjustment is required; either due to a voltage spike, internal ground/short, corrosion or whatever. The vehicle will run fine until the next adjustment is needed.
You/they disconnect the battery; the computer looses its memory but the injectors are still dirty and need to be left on longer The vehicle will now run like crap until it has been driven long enough to relearn (if capable) and or the root problem is repaired.
I wish I were better at explaining things like this and I know I’ve over simplified the example; hopefully you understand what I’m trying to say?
Here’s another way to look at this. Have you ever tried installing a new program on your PC at home and this program just won’t run? As far as you know the PC is working perfectly, has all the required hardware, no glitches or anything; it just won’t run this particular program. You take it in and the tech tells you a section of the hard drive has burnt out, the section that this program needs to run. The same thing in an automotive computer, everything is fine until a function is required that it can no longer perform.
I’m not defending your repair facility they may have left something loose like a computer ground or something. All I am saying is yes I’ve seen this before, that a computer with an internal fault runs a vehicle “normally” and then crashes. Did we cause this, no the problem was just waiting there to surface and we where the last ones working on the vehicle? We call it the ever since syndrome that some customers get. Like I said in my last post things like this are unfortunate for everyone involved. I know I would be questioning why and how this could have happened. I wish more people were like you asking questions and doing some research before going into a place pointing fingers.
Dan.
Canadian "EH"
|
|
| |
|
|
Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 25, 2006, 9:33 AM
Post #7 of 7
(1599 views)
|
|
Re: Will computers give warning before dying in 95 Jeep?
|
Sign In
|
|
With excellence Dan!
It's been a Looooong time but a car did that to me. That was the last of that and the car did re-learn after the battery was disconnected but it took a while.
Ever since I've used a memory saver on any vehicle that needs its battery disconnected and have had no problems. It's just a 9V battery and hook up to a power port/cigar lighter. This little one cannot handle a door being opened or a hood light that stays on. T
|
|
| |
|
Auto Repair Home
SEARCH
WHO'S 
LOG 
2011 Dodge Nitro OBD scanner seems to drain battery in 10-20 minutes
Grounding Cable, 2017 Jeep Renegade Trailhawk
equipment
Howdy
