After install of engine, boggy start and 4WD service light

[InterceptorF]

I reinstalled the original engine and ECU back into my 2001 Yukon XL because the engine that I re-ringed from the upullupay had bad piston slap <nightmare>. When I first got the original engine re-installed the starter would try when hooking up the battery. I discovered the battery cable was touching the start solenoid cable. After fixing that it was a boggy start but it did finally start; it then ran ok for about 10 seconds then the engine started acting funny, the service 4wd light came on and the lights on the dash dimmed out. Then it started running correct... then it dimmed out... like there is a loose connection some place? When I turned the key off, for just a second, it acted normal... dash was correct and then the service 4wd light came back on and the lights on the dash dimmed out again. It seems like I have a bad ground or a short somewhere but the grounds all seem ok and I cleaned them just for good measure. How can I discover what is going on? I have an OBD scan tool but no codes are being set.

 

[MassHoe04]

Any chance the battery got drained down below 12V?
Or... Something up with the alternator after the wire contact thing happened?

 

[InterceptorF]

I don't think so but I will check that. I did notice that the battery was dropping from 12.34 every fives seconds down a .01 amount over time like there may be a small drain on it. I am going to take the intake off and go through the harness tonight and move that stupid hidden ground on the back of the block to somewhere more convenient if I can find the time; and make sure all the wiring is ok.

 

[InterceptorF]

Ok still trying to work this out but some new developments... I repaired a seemingly good ground wire that was stock as two wires into one connector near the firewall and relocated it to the bolt that holds the dipstick in place. No change in the way the engine tries to start which is boggy The symptoms of the issue are: No lights on the selector buttons for Auto/2wd/4wd/4low, the "Service 4wd" in the Info LED is on, the Tow mode selector is lit, and now the rear windshield wiper wants to jerk around while in the off position..!? Also after initial start the battery is drained down to a point that it will not restart if turned off. Very strange.

 

[Mudsport96]

This seems like you still have a wiring issue somewhere. Sorry not much more of a help, but if things are running randomly there has to be a bad wire or a few somewhere

 

[Fless]

Have you cleaned the two grounds (three wires, two eyelets) that are on the left front body mount, next to the frame, just behind the left front wheel?

 

[rockola1971]

Verify there are no wire(s) pinched between the engine block and tranny case!!!

 

[nonickatall]

I am complete new to be the Tahoe,Yukon/Escalate world, but I am experience with other cars. So i am only guessing.

It sounds to me, that you have killed your body controller with the shortage.

That would explain the drain of the battery and the strange behavior of the rear wiper and the other stuff.

 

[InterceptorF]

SUCCESS - my battery black ground wire to the block under the cylinder 1 was the loose ground. Of course it was the last one I checked and the one I was sure I had tightened. SOLVED