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Chevrolet Express
Platform: GMT Van

2015 Chevy Express 4500 - no start

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Old Jul 14, 2019 | 1:17 PM
  #41  
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6 liter v8
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Old Jul 14, 2019 | 2:15 PM
  #42  
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However, it sounds like you didn't fully solve the electronic problems you were having. The engine may not start until you sort them out. Did you check to make sure the connections on all the modules were good like we suggested?
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Old Jul 15, 2019 | 11:16 AM
  #43  
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I took the cowling off the inside of the van and inspected the fuel rail. The rail does not seem to have a valve on it to test the pressure. My fuel rail is square and not a round tube. Am I missing it?

I have inspected the EBCM, BCM, ECM, and Airbag control module connections and cables. I still need to crawl under it and look at the connections to the TCM. I was also thinking of picking up the GM MDI 2 scan tool. They seem to be reasonable at around $200. From what I understand I will also need to get an account with 2 years of service to be able to use it.

Last edited by rockfishon; Jul 15, 2019 at 11:20 AM.
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Old Jul 15, 2019 | 2:55 PM
  #44  
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The hardware is cheap. I think they get ya on the software and license
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Old Jul 16, 2019 | 5:29 PM
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I took a look at the wiring between the ebcm and the top of the fuel tank. Everything looked pristine. I could not locate the Transmission control module. I have spark when I crank the engine. I took the fuel hose connector off to the rail since there is no test valve and have no fuel flow when I crank. It did not look like there was a check valve in the connector. I am trying to borrow the SNAP-ON reader again from my friend to see if there are any codes on the subsystems.
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Old Jul 18, 2019 | 6:12 AM
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So I hooked up the Solus Ultra and read all of the codes. Got C0055, U0100, U0140, and B1370. Cleared the codes, still did not start.

Went to test the 30 amp relay for the fuel pump. BAD relay! Put the AC relay in as a test and the engine started right up. I do not know what symptoms would show up during a slow failure of the relay, but I am trying to stay hopeful that this was the cause of all of my problems. Ordering 2 new relays just in case of future issues.

Till next time.......
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Old Jul 18, 2019 | 9:18 AM
  #47  
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Default same exact problem as rockfishon with class c rv

Rockfishon - was fuel pump relay the overall cause/solution for your no start/service airbag problem? I have a cousin class c w Chevy chassis that is doing absolute identical stuff!
R/
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Old Jul 18, 2019 | 9:40 AM
  #48  
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It is unknown if the fuel pump relay was the cause of the original problem of "no crank".
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Old Jul 18, 2019 | 12:03 PM
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Default Rockfishon solution worked for me

after I "polished" all battery clamps, posts and ground connections (no luck) I too chose the Ac relay as a sub for various other relays - for me it was a bad crank/run relay. To confirm this was the problem, I swapped the relays back and forth several times and maintained the same results. My son in law says "service air bag" is recurring msg folks see when there is a battery/crank/amp issue. Fingers crossed relay didn't blow due to another issue, had been getting worse over 10 moths w occasional relief thru a battery charge or jump or persistent starting attemps.. Anyway - thanks Rockfishon and responders for assist!
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Old Jul 18, 2019 | 12:20 PM
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rosjona1,

My relay was a OMRON, made in the USA, top number "13502750" side number "2674A11". Wondering if they had a bad batch of relays.
As a test, I am going to put this bad relay in for the RUN/CRNK on mine and see if the SERVICE AIRBAG light comes back on.

Was your relay the same part number?

Last edited by rockfishon; Jul 18, 2019 at 12:44 PM.
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