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Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 12803
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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97 tahoe 4x4: ignition switch..I can jumper the starter relay and it

Customer Question

I have a 97 tahoe 4x4 350 auto. It will not turnover with the ignition switch. I can jumper the starter relay and it will start. The ground wire for the relay is showing 12.15 volts. Also the blower motor will not work. I checked the ground wire on it also and it is showing the same voltage. If i take a put a jumper to the ground wire like it should be it gets hot in about 1 minute, but everything works. I think it is a grounding issue but im not sure were to look. I have a manual and have traced all the other wires for the relay and they are working properly.
Submitted: 7 years ago.
Category: Chevy
Expert:  Randall C replied 7 years ago.

Hello, I am a little confused , how and where are you checking grounds. lmk thanks

Customer: replied 7 years ago.
When i unplug the starter relay, the black ground wire is showing voltage. The same is showing at the blower motor ground when i unhook it . I am using a fluke digital volt meter.
Expert:  Randall C replied 7 years ago.
thanks, XXXXX XXXXX look at some diagrams. Back shortly
Customer: replied 7 years ago.
Also the antilock brake light is off until i ground the ground wire. When i ground the ground wire everything works right but i cant leave it on very long. I installed a inline 20amp fuse on my jumper ground wire and it blows after about 1 minute.
Expert:  Randall C replied 7 years ago.

You are correct about a ground issue. The grounds for each item are somehow getting tied into a power source. The big problem is there is one common ground for the blower and relay but there are alos about 20 other items that share that ground through several different splices. This problem can be very difficult to locate. The first thing you need to do is locate the main common ground point. It will be G105 in the diagram below. Right besides harmonic balancer. I would undo that ground leaving the battery ground hooked up at the same stud and see if the voltage goes away. I most likely will not. I would hate to see you have to rip apart the wiring looms to follow each black ground wire from relay and blower motor to find the short to power but you may have to. I am searching now for inline ground splices to possibly help in eliminating a large circuit one at a time. Check that ground at the engine then LMK thanks. I will also look for splices



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Expert:  Randall C replied 7 years ago.

Hello, below are the ground diagrams. You will see how many itme tie into the ground at different slice locations Eg: S108 means splice. They all then tie together and go to ground point on front of engine at G105 as i indicated in last post. I am still looking fo the splice locations



Expert:  Randall C replied 7 years ago.

I have an aidea after diagram reviews. I want you to unplug each item below, one at a time while checking a ground wire at blower or starter relay. watch your meter. If you drop the voltage after you unplug one of the items, we can zero in on the bad circuit.


Unplug one at a time:


AC comp relay

Stop lamp relay

Brake controll module ( location #3 below)


LMK if by doing so at anytime the power on the ground wire goes away