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1998 5.7 GMC Van P1351, PO171, PO174


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b_oneself
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Mar 13, 2012, 8:50 PM

Post #1 of 72 (7044 views)
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     1998 5.7 GMC Van P1351, PO171, PO174  

OK,
I'm having a problem with my engine again. After a long complicated self-inflicted detour concerning a fuel pump pressure problem I finally got it straightened out thanks to the marvelous genius - and generous Hammer Time. I've been rolling along just fine (although I kept getting a periodic check engine light on - same old PO171 & PO174 trouble fault codes but these have not deterred me from having plenty of power) and then suddenly today the engine won't fire. I have to presume the problem is on the spark side since I can hear the fuel pump pre-loading and running when the key is in the start mode. Plus I sprayed starter fluid directly in air intake (air cleaner) and got nada, not one explosion. Borrowing my friend's code scanner I pull up trouble code P1351 (High voltage Coil # 1 and Coil#4) Could this mean I am getting no spark and thus no start?


(This post was edited by b_oneself on Mar 14, 2012, 8:15 PM)


Hammer Time
Ultimate Carjunky / Moderator


Mar 13, 2012, 9:07 PM

Post #2 of 72 (7016 views)
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     Re: 1998 5.7 GMC Van PI351, PI171, PI174 [In reply to]  

Are you sure about that P1351. It doesn't make a whole bunch of sense.


The other 2 codes aren't right either. They have t have been PO171 and PO174




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



b_oneself
User

Mar 13, 2012, 9:29 PM

Post #3 of 72 (6993 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

I guess you must be right (I am not at the vehicle now or I would double check) Must have been PO171, PO174 -a lean code for Ox sensors either the upstream or downstream ones, Bank 1 and Bank 2 or something like that. I already replaced one set, before or after.. and as I mentioned this appears to be of secondary concern at the moment, since I have to start the van in order to go to work. P1351 That must be it. I wondered about the crankshaft position sensor. I feel like I am wandering around in the dark. This is no VW beetle (my only repertroir of mechanical know-how).


(This post was edited by b_oneself on Mar 14, 2012, 8:16 PM)


Hammer Time
Ultimate Carjunky / Moderator


Mar 13, 2012, 9:32 PM

Post #4 of 72 (6988 views)
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     Re: 1998 5.7 GMC Van PI351, PI171, PI174 [In reply to]  

That wouldn't mean bad 0/2 sensors. That's a lean condition. Check for vacuum leaks or intake snorkel leaks.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



b_oneself
User

Mar 13, 2012, 9:52 PM

Post #5 of 72 (6966 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Thanks for being there once more, most honorable Hammer Time -and so quick to reply! I believe you that I need to replace the other two O/2 sensors. This little problem persisted even after you got me on the road again last time. But I have been driving it ever since. This new condition (won't start -seems like no spark) is what has got me parked. What can P1351 refer to (High voltage Coil #1 & #4). This is the only new code to appear so without making the mistake of throwing money at the entire list of faults, I hoped to narrow down my focus to this most urgent one. -Or are you saying that the O/2 problem might have caused the starting problem?


(This post was edited by b_oneself on Mar 15, 2012, 11:35 PM)


Hammer Time
Ultimate Carjunky / Moderator


Mar 13, 2012, 9:58 PM

Post #6 of 72 (6962 views)
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     Re: 1998 5.7 GMC Van PI351, PI171, PI174 [In reply to]  


Quote
I believe you that I need to replace the other two O/2 sensors.


Where did I say that?

I said exactly the opposite that the sensors are fine. You have a lean condition that the sensors are reporting.

There is no PO351. You need to get the code right before you do anything. We could be chasing the totally wrong codes.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



b_oneself
User

Mar 13, 2012, 10:23 PM

Post #7 of 72 (6936 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Oops, I reread the post and you're correct. You said the O/2 sensors would not be the issue, and yes, as a matter of fact I know I have a little vacuum leak because the hose that attaches to that plastic vacuum "storage" canister came off at the intake area and I cannot see where it belongs. With that said, it sure seems like this is a separate issue from the starting problem - especially since it has been in this condition since we (you) last got this GMC 3500 Econoline van back running with plenty of power. I apologize for being so sketchy with the trouble codes. I will recheck them first chance I get. I think I must have read P1351 -I definitely remember the description: High voltage Coil #1 & #4.


(This post was edited by b_oneself on Mar 14, 2012, 8:20 PM)


b_oneself
User

Mar 14, 2012, 10:44 PM

Post #8 of 72 (6832 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

I have now rechecked the trouble codes and this is finally, for sure, the correct readings:
PO171 and PO174 (a lean reading from the O/2 sensors) and I did find a couple of vacuum leaks so I'm hoping this could resolve that particular problem. However, I am still unable to start the engine so I cannot determine that. But the scanner is clearly showing P1351 (no codes present with key on engine off but P1351 appears every time I engage the starter. I have repeated the test many times over and it always states: P1351 Ignition coil #1 and #4 control circuit high voltage Any clues anyone? I am sorry about the confusion regarding the errors in my trouble code reporting.


Hammer Time
Ultimate Carjunky / Moderator


Mar 14, 2012, 10:45 PM

Post #9 of 72 (6830 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

What's the fuel pressure?

That code still can't be right. you truck doesn't even have "coil 1 and 4 control circuits. It has one coil and one circuit.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



(This post was edited by Hammer Time on Mar 14, 2012, 10:48 PM)


Discretesignals
Veteran / Moderator


Mar 14, 2012, 11:03 PM

Post #10 of 72 (6819 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

P1351 is IC (ignition control) circuit high voltage.

That P1351 code maybe why the engine doesn't start. That code usually pops up when the PCM sees above 4.9 volts on the IC circuit going to the ignition module. The PCM uses the IC circuit to trigger the transistor in the ignition control module to fire the ignition coil.

This is what the diagnostic chart states:

Inspect the wiring and connector at the IC module. Make sure that the IC module is plugged in.

* Take a volt meter and set on it AC volts. Remove the connector from the ignition module and probe the white wire terminal in the connector. Connect your meter's black lead to battery negative. Have someone crank the engine. You should see 1-4 volts.

If you see 1-4 volts, set your meter on DC volts and check for battery voltage on the pink wire in the connector with the ignition on.

If you see battery voltage on the pink wire, set your meter for ohms and check the black wire for continuity to ground. It should be close to zero ohms.

If everything checks out good, replace the ignition control module.


* I question this step because the signal from the PCM is a digital on and off signal in DC volts. Could be in error, but that is what is written in the step.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 15, 2012, 12:28 AM)


b_oneself
User

Mar 14, 2012, 11:30 PM

Post #11 of 72 (6810 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Oh boy. I don't know if you recognize this thread being related to that one entitled "power problem" from back in early Jan. That was the one where you (Hammer Time) walked me through a long process of diagnosing, in the end, a bad fuel pump (because I kept jumping to conclusions prematurely) Naturally, since I did eventually replace the pump -which corrected the problem *thank-you very much*, and because I observed the pump currently working during pre-load and in starting mode I didn't even consider the possibility of a fuel problem. Plus, I injected starter fluid into the intake boot at the air cleaner and still no combustion. Nevertheless, fuel pressure is a fair question -if only to eliminate that fundamental concern (min. 55psi). So I'll go borrow that "known working" fuel pressure tester and confirm I've got enough. Still, I am wondering if that P1351 code isn't spark related. Despite my attempt to eliminate the PO171 & PO174 -(and you pointed to the vacuum leaks I found), this engine has been starting and running great ever since the fuel pump fixed the "power problem" in Jan. It suddenly stopped starting yesterday. To be continued...when there is more info/ideas


b_oneself
User

Mar 15, 2012, 12:13 AM

Post #12 of 72 (6806 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Discrete One and Hammer Time,
I should also like to add that we did replace the dist. module, the coil, and the pick-up in the dist. at the same time ( just previous to) the corrective repair, i.e., the fuel pump. (We also replaced wiring to the fuse box "relay station", the fuel pump relay, the fuel pressure regulator, spark plugs, upstream O/2 sensors, checked for blockage in the exhaust & more - cf. "power problem" (Jan. 6, 2012) I'm going to try and carefully follow the advice I am gratefully receiving from you two. I'm also trying to apply a little logic and add some common sense to the puzzle at present, and given the limitations of resources.(I do have a good volt-om meter)
Much appreciated, Bob


Discretesignals
Veteran / Moderator


Mar 15, 2012, 12:15 AM

Post #13 of 72 (6806 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

You probably don't have any spark, since spraying the intake didn't make the engine start, pop, or do anything.

If your getting that P1351 code which sets when the engine is cranking all the time, that probably means that the PCM can't signal the ignition control module or the ignition control module died. Testing would verify that. You could have a defective ignition control module even though it is a replacement. The ignition control module also needs a light coat of thermal paste when you screw it to the heat sink. You don't paste it and it will burn up or fail early.

No ignition module activity, power or ground missing to the module, open in primary circuit from the coil, or no trigger signal to the module from the PCM and you won't have any spark. Of course, an open in the primary circuit from the coil won't cause a P1351.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 15, 2012, 12:31 AM)


b_oneself
User

Mar 15, 2012, 12:34 AM

Post #14 of 72 (6793 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Gotcha. That's where I think I should go next. (I did the thermal paste thing, but maybe I did it wrong or maybe the part is defective?) Thanks for the suggestions. Both of you, -all of you. What a great forum!


(This post was edited by b_oneself on Mar 15, 2012, 11:41 PM)


Hammer Time
Ultimate Carjunky / Moderator


Mar 15, 2012, 5:59 AM

Post #15 of 72 (6785 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

My fuel pressure question was triggered by the lean codes




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



b_oneself
User

Mar 15, 2012, 9:28 PM

Post #16 of 72 (6753 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Gurus,
I did the recommended tests according to the diagnostic chart.
step#1
measured the white wire on end of connector (the order of connector wires: white, black, white, pink)
result was virtually no voltage except an instantaneous surge -(less than a split second) when I began cranking the starter -during the cranking no voltage on both AC and DC scales
measured the white wire in middle of connector (#3 next to pink one)
result was between 1-4 volts on both the AC and DC scales

step#2
measured the pink wire and (at end of connector)
result was almost 12 volts on DC scale
step#3
measured continuity between black wire and ground on ohm scale and got 0.00 on each om level except 200M

We replaced the ignition module (taking special care to apply the thermal paste) and coil (since it was a free exchange) and when that didn't start the engine we replaced the crankshaft position sensor . Still nothing. Now what? Please don't tell me it could be the PCM. The business about the AC scale did seem strange, plus I'm still not certain WHICH white wire is the correct one to test. I also checked for spark at the spark plug wire and definitely no spark.


(This post was edited by b_oneself on Mar 15, 2012, 11:53 PM)


Discretesignals
Veteran / Moderator


Mar 15, 2012, 10:00 PM

Post #17 of 72 (6747 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

After clearing the code, does it reappear each time after you crank the engine for thirty seconds? Unplug the injector connector, clear the code, crank the engine for 30 seconds, and see if the code comes back.

Inspect your connector really good. Look for broken wiring inside the insulation near the connector by slighly tugging on the wires to see if the insulation stretches and inspect the terminals in the connector. Make sure the terminals have good tension.

Have you checked for spark using a spark tester?

The ignition control module connector should have letters on it. A-D

A(pink): 12 volt source from ignition. Hot when ignition is run or start.

B(white): IC trigger. Should have between 1-4 V while cranking the engine.

C(black/white): is the ground for the module.

D(white/black): Ignition coil trigger. Should see 12 volts with ignition turned on.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 15, 2012, 10:45 PM)


b_oneself
User

Mar 15, 2012, 10:37 PM

Post #18 of 72 (6737 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

D.S.,
I did clear the code several times (within the scanner tool) and the P1351 did reappear each time. I never unplugged the injector connector -(location?)

I did inspect the connector to the ignition module very carefully, the wires seem tight with no breaks, but I'll double check again.

My method for checking the spark was the old fashioned way -stick a screwdriver in the spark plug wire and hold the metal of the screwdriver 1/4 inch away from ground and watch for a spark to jump to the ground.

I didn't see the A-D letters on the connector (I will look thoroughly tomorrow). But I clearly could see the order and color of wires. On this connector: Pink, then white, then black, and white on the other end. Also this second description of wire color/order is different from your first diagnostic chart. One more little clue I just thought of: This whole no spark/ no start condition just began 2 days ago after it rained all night -the first time it has really rained hard in months.

(This post was edited by b_oneself on Mar 15, 2012, 10:41 PM)


Discretesignals
Veteran / Moderator


Mar 15, 2012, 10:44 PM

Post #19 of 72 (6732 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Sorry, I didn't quite have them in order in the previous post.

This should clarify things:







Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


b_oneself
User

Mar 15, 2012, 11:15 PM

Post #20 of 72 (6724 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

As best as I can figure:

My pink wire is hot (12 volts) with key on and during cranking
My middle white wire is getting the 1-4 volts during cranking
My black wire is a good ground (no resistance)
My end white wire has virtually no volts (.02) with key on or during cranking -that would be D the terminal for the tachometer signal according to the diagram. You mentioned it should be putting out 12 volts to the coil (correct?) but for this test I would have check the wire while it was plugged into the ICM (correct?) Otherwise, if I am supposed to check the end white wire (D) on the connector that goes to the ICM without it being plugged into the ICM, then I've got nothing with key on or during cranking. Btw, is the vehicle control module (VCM) the same as the powertrain control module (PCM) ie., the computer?


Discretesignals
Veteran / Moderator


Mar 15, 2012, 11:38 PM

Post #21 of 72 (6719 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

With the ICM connector unplugged and the ignition switch in the run position you should see 12 volts on the white/black wire (D). The module doesn't supply battery voltage to coil. The module grounds that circuit to charge the coil or saturate it. When the module gets the signal from the VCM to fire the coil, it unlatches the ground.

The power for the ignition coil comes from the ignition switch. If you have no power on the terminal (D) and your coil is good, you have a wiring problem because you know you have power on the pink wire from the terminal.

Pull the ignition coil connector and check for 12 volts with the ignition in the run position on the pink wire (A). Then ohm check the white/black wire between the ignition coil and ignition module(C to D). Inspect your wiring and connectors very carefully.

The PCM and VCM both control the operation of the transmission and engine. The only difference is that a VCM also controls an ABS system. What is funny is that GM must of been confused and stuck with the VCM name for the controller even though it doesn't control the ABS system on your van. The ABS system is controlled by the EBCM.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 16, 2012, 12:26 AM)


b_oneself
User

Mar 16, 2012, 12:23 AM

Post #22 of 72 (6705 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Discretesignals,
Thanks for the precise instructions and helpful corrections. I will have to pick this up again tomorrow when I can return to the van. I do recall the D wire did not have 12 volts (none) with the key in run position. So it looks like I must examine the wiring as you say. Because of your attention I now have some good directions to hunt down the culprit! I shall report back on my investigation. If only I could get some new eyes.


b_oneself
User

Mar 16, 2012, 9:11 PM

Post #23 of 72 (6678 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

OK,
Here's the latest update on my no start/no spark condition. After double-checking with the volt/ohm meter I got exactly the specified readings on the ICM connector and the coil connector. ie., 12 volts on the pinks, between 1 and 4 volts on the middle white (B) during cranking, no resistance on the black (C) and 12 volts at (D) with the key on, and no resistance between (C) and (D). It still won't start -no spark, and the same P1351 code is present after cranking the starter 30 seconds. Remember I just finished changing the ICM and coil (twice) and the crankshaft position sensor. Where do I go from here?


Discretesignals
Veteran / Moderator


Mar 16, 2012, 9:44 PM

Post #24 of 72 (6675 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

We are now off the trouble chart. You have an odd one here.

Just for the heck of it inspect the ground eyelet for the module. It is bolted on the inside of the fender near the master cylinder. There is another ground you should check that attaches to the right inner fender next to the battery. This ground goes directly to the negative battery cable. Make sure they are clean and tight.

Do you have a 12 volt test lamp? If you do, unplug the coil connector. Then connect your test lamp to the positive side of the battery and probe the white/black wire (pin C) in the coil's connector. Have someone crank the engine. Does the lamp flash rapidly?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 16, 2012, 9:49 PM)


b_oneself
User

Mar 17, 2012, 4:07 AM

Post #25 of 72 (6657 views)
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     Re: 1998 5.7 GMC Van P1351, PO171, PO174 [In reply to]  

Thank-you for following my peculiar problem with the no spark/no start syndrome. I shall do the recommended procedures when I return to the vehicle. It was pouring rain when you posted last so I will carry on tomorrow. I can use all the help I can get. You're an unique resource and perhaps have no idea the value of the education you provide, along with that other master I encountered, Mr. Hammer Time.
With respect for your work and a grateful user of CarJunky. com advise,
Bob


(This post was edited by b_oneself on Mar 17, 2012, 4:08 AM)




1998 5.7 GMC Van P1351, PO171, PO174


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