NEED HELP 2006 TrailBlazer "Crank no start"

[Mikefred7370]

2006 Trail Blazer. My brother jumped the gun and blasted it with the "Parts shotgun" but not just any parts shot gun, no he pulled out the double barrel parts shot gun and paid out nearly a $1000 bucks including a ECU, A fuel pump and throttle position sensor and throttle body. I tried taking a trip down the diagnosis path and tested the Fuel pump relay, fuse check and I can get it to run by jumping the relay and it runs fine that way. I currently have a jumper wire installed on a circuit that only has voltage when the key is on and I've run a few times without any issues keeping in mind the gauge of wire to avoid overheating the wire or causing more damage and the the wire never got warm the times I've needed to run it but I don't like the idea of leaving it that way, Any help would be greatly appreciated. Thanks.

 

[Mooseman]

Hi and welcome.

There should be licenses for the parts shotgun. Total waste.

We get lots of those here (one of these days, I'm gonna have to do either a write up or a collection of these threads). This search will bring up most of them:
https://www.google.ca/search?newwin...131k1j0i10k1j0i22i30k1j33i160k1.0.xObh8dl8ikY

 

[Sparky]

Sounds like a bad relay or maybe the relay socket, perhaps.

 

[Mooseman]

This video is from one of our alumni (please excuse the foul language):

 

[Mikefred7370]

I watched his video several times, it was him mentioning GMT in the video that led me to your forum...Great guy, But to the issue at hand it didn't didn't solve the problem. I did some research this evening and I'm lm going to pull the fuse box out completely and look for any signs of corrosion or heat damage, I noticed this evening if I have someone crank the engine while I wiggled the Fuel pump replay it seemed to kick the fuel pump on. Thanks for the help to this point, it's nice to know there's help out there. I'll post tomorrow to update on what I find.

 

[Mikefred7370]

Ok I got a trouble code that says primary fuel pump circuit. I used a wire as previously mentioned to jump the relay, It ran fine. As it was running and with the scan tool hooked up I only got a code for engine tempature sensor and another that the Crank shaft sensor needed to be relearned. But I decided to see if another code would pop up if I disconnected the jumper wire and sure enough I got a primary fuel pump circuit code. I took the fuse box apart and could not find any signs of corrosion or heat damage so I put it back together. I'm at a standstill now. I don't see how it could be in the wires back to the tank since the pump kicks in fine with a jumper. I know I have power from the ignition to the relay as I already tested that... Could this still be a bad ground issue somehow?

 

[I_Shoot_Back]

I noticed this evening if I have someone crank the engine while I wiggled the Fuel pump replay it seemed to kick the fuel pump on.

spade connectors in fusebox sloppy,not clamping on the relay legs enough? If you twist the legs from the relay a tad so they go into the connector a bit stiff,that might help?

 

[mrrsm]

In an unrelated thread in which the SUV GM 4.2L Engine was suddenly cutting off when the vehicle steering was engaged during a sharp turn... there was some mention that the Fuel Pump and the Ignition Switch ...share a Common Ground. If you think Engine Grounds might be involved in your present circumstance... here is a Diagram of All Four Grounds clustered on the Driver's Side of the Engine Block. It will not hurt to examine them all of them for any corrosion or looseness:



Also... You probably already have the GM OEM Shop Manual ... But if not... Check out this link to be able to Download one specific to your Vehicle. It would not hurt scouting the Electrical Circuit Diagrams related to this problem.

https://gmtnation.com/forums/threads/need-service-manuals-get-them-here.361/

...and perhaps you should substitute a short wire , Fuse-able Link in your Jumper Wires in case it turns out that the PCM is involved in the output side of that circuit. Better to be Safe than Sorry. Here is where to grab a few...and be sure to get a wide range of Fuses for other applications while you are at it:

https://www.amazon.com/dp/B01DYPY0E4/?tag=gmtnation-20

 

[Mikefred7370]

Thanks. I will check that out. Ive been going through the wiring and I can now get it running without a jumper wire but it's now over heating the relay and shuts back down after 3 minutes or so...so I'm thinking it's probably a poor connection and the resulting resistance from the poor connection is overheating the relay? I don't think it's a short but again wiring Gremlins can throw you off.

 

[Mooseman]

It could alao be something in the wiring downstream from the relay, either the wiring itself, a connector or possibly the pump itself creating high amps. In that rampage with the parts shotgun, was the relay replaced or swapped with another?

 

[Mikefred7370]

Well I'm not ready to say it fixed 100 %, but it is running and stayed running fo 2 hours . I went through the wire harness and found a bare spot on a wire and repaired that with shrink tube and installed new wire loom and used zip ties to keep it from rubbing through again. That section of the harness connects to the middle connection on the PCM . I also pulled the power distribution box apart and installed new tabs on the inside , I only did the tabs for the fuel pump relay. I also checked grounds and harness connectors that I thought may have to do with the fuel system and the PCM connectors , I used the air compressor to to blow the dust and debris off then cleaned them all with Electrical parts cleaner and finished with dialectic grease. I tightened everything up and hit the key , Fingers crossed...and it seems to be fixed. I appreciate all your help and I honestly think member I_shoot_,back hit the nail on the head with his suggestion to slightly twist the prongs on the relay to make it fit tighter . That's a great suggestion and honestly I think that was the main issue. I just didn't want it happening again so I went one step further and replaced the tabs inside the box. I can't say for sure weather it was the other work that I did or if it was a poor connection at the relay but for future reference that's something that should be checked first because I've seen a ton of similar issues here and on other sights.I only wish my brother would have listened to me in the first place but money's not an issue to him so he has no problem using the double barrel parts shot gun..I'll keep posting over the next few days to let you know if there's any reoccurring issues.

 

[Mooseman]

I wish I had a brother like that. Good work.

 

[Mikefred7370]

Yeah... He's drawing $500 a day , Heavy equipment operator, Union . Plus all the rental property's he owns and his girlfriend is a nurse making bank too...Sad thing is the Trail Blazer is just an extra vehicle, She has an Explorer and a Chevy Cobalt plus 3 Harleys and he has a 2017 F150 with that Coyote engine package , an F250, A Harl

Accidentally hit post before I finished lol. Anyway the point is it's a backup vehicle for his girlfriend and he works mad hours so he doesn't have the time or the patience to do diagnosis things....and the kicker is he BOUGHT a turn key repair shop with lifts and all the equipment so any time one of their vehicles go down they have it at their disposal...

 

[Mooseman]

Nice. I hope he lets you use the garage when you need it.

BTW, you can use the Edit button. I merged the posts for ya.

 

[Mikefred7370]

Thanks. Oh yeah..He let's me. Pays me as well plus use of the vehicles and campers.