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#4465285 - 07/20/17 06:20 PM Chevy Express 4500 intermittent crank no start
Burt Offline


Registered: 01/08/09
Posts: 1311
Loc: texas
I have a 2012 chevy express 4500 motor home with 46,000 miles and am in the middle of a 7,000 mile trip from Texas to Nova Scotia and back.

about 6 weeks ago, I checked into a campground and turned the key - it cranked but the fuel pump relay didn't energize. A former fleet manager was on site and banged on the tank and we pulled and reinserted the fuses and it restarted was good for a month.

Happened a month later and it was at the entrance to a national park on a sunday. Tow truck driver thought he found a loose fuel pump connection and it started.

Two days later it happened and technician read OBDII codes and found 3 codes: security key disable, brake computer module miscommunication, ecm miscommunication. no dashboard idiot lights. cleared the codes and the latter two came right back. Said next time switch keys.

Now it happens twice a day. At first switching keys worked like a charm. But not today. Today I opened and closed the door, moved the turn signal, and left ignition on for a few minutes and it restarted. Truck seems to have less power, mpg has dropped 15-20% and it stalls or threatens to stall.


I've been to 3 chevy dealers. All say engine codes are virtually meaningless, it could be one of a dozen things, many of which would cost $800 a pop. unless what ever it is causes total failure, they say they haven't a clue what to do. All say drive it till it totally fails (in the hinterland?!) pay a serious tow truck $500+ to tow it to the nearest dealer and hope the problem doesn't go away by the time they look at it and by the way they are booked for the next week. This is beyond the capabilities of a regular truck shop. One service manager thought the notion of driving til it stranded me was funny.

I find this unacceptable. An RV is not a car that you can rent or borrow another. It by definition is a long ways from home and it dies you can't push it out of an intersection, entrance etc. Called GM of Canada customer service and she said don't expect her to diagnose it, gave me sympathy and thought the dealer ought to play with it till it shows symptoms, which they are unwilling to do.

I can't believe that with all the technological expertise GM has, it's computers don't record why they are temporarily shutting down the fuel pump - only on warm starts.

Any words of experience appreciated - please no shot in the dark responses.
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2011 RX350 53k miles
2015 Fiesta SFE eco-boost 24k miles

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#4465287 - 07/20/17 06:25 PM Re: Chevy Express 4500 intermittent crank no start [Re: Burt]
L_Sludger Offline


Registered: 10/04/09
Posts: 3947
Loc: Ohio
In my experience, your symptoms have led to a faulty crankshaft position sensor in two different cars: A mid-2000s Jeep Grand Cherokee and a mid-2000s Mercedes S430.
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#4465295 - 07/20/17 06:29 PM Re: Chevy Express 4500 intermittent crank no start [Re: Burt]
HangFire Offline


Registered: 08/21/13
Posts: 2506
Loc: Central Maryland
This guy's story with his 2011 Chevy Van may be of interest:

http://imgur.com/gallery/kBTT0/

Unless you're really lucky, shot in the dark responses may be all you get.

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#4465298 - 07/20/17 06:30 PM Re: Chevy Express 4500 intermittent crank no start [Re: L_Sludger]
Burt Offline


Registered: 01/08/09
Posts: 1311
Loc: texas
Originally Posted By: L_Sludger
In my experience, your symptoms have led to a faulty crankshaft position sensor in two different cars: A mid-2000s Jeep Grand Cherokee and a mid-2000s Mercedes S430.


how did you diagnose? wait til it failed and tow them in?
_________________________
2011 RX350 53k miles
2015 Fiesta SFE eco-boost 24k miles

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#4465301 - 07/20/17 06:33 PM Re: Chevy Express 4500 intermittent crank no start [Re: Burt]
L_Sludger Offline


Registered: 10/04/09
Posts: 3947
Loc: Ohio
Originally Posted By: Burt
Originally Posted By: L_Sludger
In my experience, your symptoms have led to a faulty crankshaft position sensor in two different cars: A mid-2000s Jeep Grand Cherokee and a mid-2000s Mercedes S430.


how did you diagnose? wait til it failed and tow them in?

Well, there was no towing involved, just waiting for the cars to start again, due to the intermittent nature of the fault. The Jeep was a pretty easy fix, the Mercedes needed some tools but otherwise wasn't too bad. The part is cheap. Why not try it? Yeah it's a shot in the dark, as a previous poster said - but its WAY cheaper than a tow!!!
Diagnosis was done with some discretionary Googling of the symptoms and the car's make and model and year. Both came up with the crank sensor as a common fault causing this common issue, and the CPS replacement solved it on both occasions. smile
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#4465314 - 07/20/17 06:42 PM Re: Chevy Express 4500 intermittent crank no start [Re: HangFire]
Burt Offline


Registered: 01/08/09
Posts: 1311
Loc: texas
Originally Posted By: HangFire
This guy's story with his 2011 Chevy Van may be of interest:

http://imgur.com/gallery/kBTT0/

Unless you're really lucky, shot in the dark responses may be all you get.



This guy did some serioius diagnostics on it. Something the service reps are unwilling to do.


Edited by Burt (07/20/17 06:43 PM)
_________________________
2011 RX350 53k miles
2015 Fiesta SFE eco-boost 24k miles

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#4465346 - 07/20/17 07:07 PM Re: Chevy Express 4500 intermittent crank no start [Re: Burt]
Linctex Offline


Registered: 12/31/16
Posts: 6148
Loc: Waco, TX
Originally Posted By: Burt

This guy did some serious diagnostics on it. Something the service reps are unwilling to do.


Only a good mechanic with a LOT of experience, and knows how to do PROPER troubleshooting and diagnostics, will be able to fix it. and it likely won't be cheap - - - -

but I'd rather pay to have it fixed right than be stranded in the middle of nowhere - - -
at the mercy of some dude that really has no idea how to fix it.
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#4465384 - 07/20/17 07:34 PM Re: Chevy Express 4500 intermittent crank no start [Re: Linctex]
Burt Offline


Registered: 01/08/09
Posts: 1311
Loc: texas
Originally Posted By: Linctex
Originally Posted By: Burt

This guy did some serious diagnostics on it. Something the service reps are unwilling to do.


Only a good mechanic with a LOT of experience, and knows how to do PROPER troubleshooting and diagnostics, will be able to fix it. and it likely won't be cheap - - - -

but I'd rather pay to have it fixed right than be stranded in the middle of nowhere - - -
at the mercy of some dude that really has no idea how to fix it.



Wholeheartedly agree! But if three dealers and GM "customer service" turn me down, where do I go? That's really my point. BITOGer's want to fix it themselves or shoot in the dark, but I need someone with real expertise that is willing to roll up their sleeves and use proper diagnostics. How do I find a person like that in Quebec, Ontario or in Northwest NY?
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2011 RX350 53k miles
2015 Fiesta SFE eco-boost 24k miles

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#4465408 - 07/20/17 07:52 PM Re: Chevy Express 4500 intermittent crank no start [Re: HangFire]
ls1mike Offline


Registered: 06/14/08
Posts: 5118
Loc: In the Garage...
Originally Posted By: HangFire
This guy's story with his 2011 Chevy Van may be of interest:

http://imgur.com/gallery/kBTT0/

Unless you're really lucky, shot in the dark responses may be all you get.

Did you read the back story on that...The customer tried jump starting it from a 36V system
Oh my!
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00 Trans Am WS6 5.7 LS1
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#4465413 - 07/20/17 07:55 PM Re: Chevy Express 4500 intermittent crank no start [Re: Burt]
ls1mike Offline


Registered: 06/14/08
Posts: 5118
Loc: In the Garage...
Your codes are very similar to a bad BCM, but with out being able to data log it is hard to tell.

A faulted CPS on GM will give you some different codes and usually a flashing check engine light.

Have you had a check engine light or flashing check engine light?

Does it sit often? Have you checked the harness for and critter damage?

It is an RV so I am going to assume it sits.

Is this a 6.0?
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00 Trans Am WS6 5.7 LS1
02 Silverado 2500HD 6.0
14 Caprice PPV 6.0
15 Malibu LTZ Turbo
12 Passport TT

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#4465490 - 07/20/17 08:59 PM Re: Chevy Express 4500 intermittent crank no start [Re: ls1mike]
Burt Offline


Registered: 01/08/09
Posts: 1311
Loc: texas
6.0 that sits months at a time

No cel's, lack of which confounds service reps. They are only interested in obvious easy to spot problems.
_________________________
2011 RX350 53k miles
2015 Fiesta SFE eco-boost 24k miles

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#4465494 - 07/20/17 09:03 PM Re: Chevy Express 4500 intermittent crank no start [Re: Burt]
cpayne5 Offline


Registered: 12/28/05
Posts: 605
Loc: Virginia
Where's your route taking you? Through New York and PA, perhaps?

There's a few YouTubers in that area (Eric O of South Main Auto - Avoca, NY, Ivan of Pine Hollow Auto Diagnostics - State College, PA, and ScannerDanner - Pittsburgh) who are top notch automotive diagnosticians. They may be able to help if you can get in touch with them (which I'm sure a few people here could help you with).


Edited by cpayne5 (07/20/17 09:05 PM)

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#4465531 - 07/20/17 09:37 PM Re: Chevy Express 4500 intermittent crank no start [Re: Burt]
ls1mike Offline


Registered: 06/14/08
Posts: 5118
Loc: In the Garage...
Originally Posted By: Burt
6.0 that sits months at a time

No cel's, lack of which confounds service reps. They are only interested in obvious easy to spot problems.


Really look at your wires I had some sort of rodent in my truck and it was acting up. Found he ate through some wires.
Mine sits for months, just tows my trailer. I had no CEL but a sometimes no start or stall. Ate some wires that I didn't see. I just started doing continuity checks and found 6 or 7 wires eaten through.

In general unless something happened they are reliable. It sounds BCM or ECM.

Did you say the year and I missed it?
_________________________
Mike
00 Trans Am WS6 5.7 LS1
02 Silverado 2500HD 6.0
14 Caprice PPV 6.0
15 Malibu LTZ Turbo
12 Passport TT

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#4465533 - 07/20/17 09:37 PM Re: Chevy Express 4500 intermittent crank no start [Re: Burt]
ls1mike Offline


Registered: 06/14/08
Posts: 5118
Loc: In the Garage...
Ok 2012. Let me look, I have a pretty good amount of LS guys who know this stuff.

Another common one in the vans is the ignition switch.
_________________________
Mike
00 Trans Am WS6 5.7 LS1
02 Silverado 2500HD 6.0
14 Caprice PPV 6.0
15 Malibu LTZ Turbo
12 Passport TT

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#4465624 - 07/20/17 11:08 PM Re: Chevy Express 4500 intermittent crank no start [Re: cpayne5]
TheBeaz Offline


Registered: 07/14/17
Posts: 22
Loc: MN, USA
+1 Totally agree with that. I would first try to contact scannerdanner at Rosedale technical Institute outside of Pittsburgh since he is familiar with RV's and is probably one of the best advanced electrical and computer diagnostics teacher in the country.

https://www.youtube.com/channel/UCrf6f8hn5oy4alB2WXJCIqA

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