No Start - Failing Indicator Bulb Test?

[iridektm]

Hey guys so I am at the tail end of my Cummins/nv4500 swap into a 2000 GMC gmt400. I deleted the ABS computer, all the automatic transmission wires and engine related parts of the harness. I was very thorough and careful with what I chose to keep and remove. I went to crank it for the first time and nothing happened.

Started by tracing wires making sure they are going to the right places. I have continuity between the right wires and their destination at both the starter relay and fuel pump relay. The fuel pump won't prime with key on and when I turn the key to start, nothing happens.

I have been studying the diagrams for hours and attempting to figure out what the issue is. I believe I am failing the indicator bulb test as my Brake warning Lamp and ABS lamp do not come on when the key is turned to run. I cut both of those wires coming out of the C100 firewall connector and closed them off. When I turn the key to start, the brake lamp lights up then goes back off when the key is returned to run.

Will not having the brake warning lamp and ABS lamp on the dash cause a no start? Or just one of them? I grounded the brake lamp off of the DRL module and the light came on but stays on and still no crank.

Is there a way to bypass the indicator bulb check test? Does the warning lamp need 12v instead of the ground. I can't seem to find the wiring diagram for the test even on Alldata.

In this diagram you can see circuit 33 the tan/WHT wire terminates in the ABS computer. That has been removed but I'm not sure what it sees in the computer to make it pass the test.



If anyone has any insight to this issue that would be greatly appreciated!

Thanks!

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[iridektm]

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[SAATR]

So I take it that you have bypassed the PN position switch entirely, and have good continuity between the CRANK fuse and terminal 85 of the relay? Also have good switched power at the relay when the key is in the start position? I think that the fuel pump relay is grounded by the engine ECM. Did you install a constant ground to circumvent that? I honestly don't think the bulb check has anything to do with the issue.

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[iridektm]

Thanks for the response I believe I found the issue after taking a day off of the truck and then spending 30 minutes with it tonight.

After all that wire chasing, diagram studying and thinking I have no clue what's going on with 12volts...

One problem turned out to be swinging to many hammers under fender wells without ear protection. The fuel pump has been priming the entire time and I was chasing a problem that didn't exist.

The second issue is a bad starter. It started the motor in the garage on the stand so I completely ruled it out. Turns out every stud was grounding out and getting hot. I pulled the started and starter pulling it apart when I thought to hook up an old 5.7 starter with the way I have everything wired. Turned the key and what do you know, she spins.

I do have a much better understanding of the wiring in the truck now and reading diagrams/chasing wires so it turns out to be a win/win.

And to answer the question, apparently the truck does not need to pass the indicator bulb test!

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[SAATR]

Hearing protection, it's that important! I've lost a good bit of mine running impact guns for years with no ear plugs, that and loud concerts. Glad you got everything sorted!

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[iridektm]

And I'm only 25 to boot... Can't be a good sign, but it is a pretty quiet pump haha. Either way glad I don't have to undo my nice looming job!

Thanks again!

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