Wiring Harness Grounding
#1
10-22-2011, 01:14 PM
Wiring Harness Grounding
I had an issue with my 2000 GMC Jimmy shutting off randomly. If I messed with the wiring on the back side of the engine, I could get it running again but would still shut off again randomly. I started pulling the wiring harness out and realized where the harness bolts to the engine for grounding, the bolt was loose. Is this really the problem or should I keep looking?
2000 GMC Jimmy 4.3 ltr V6 4x4
What sort of sensor would cause the engine to shut off if this isn't the problem?
Thanks,
Matt
2000 GMC Jimmy 4.3 ltr V6 4x4
What sort of sensor would cause the engine to shut off if this isn't the problem?
Thanks,
Matt
#2
10-22-2011, 01:28 PM
There's no magic or crystal ball for wiring problems.
All wiring harness grounding points are critical. If it doesnt happen anymore then that was it.
Besides that, to rule out possibilities of problems more difficult to solve than that one..
All vehicles should have three grounding cables:
- NOT counting harness grounding points. These are discrete wires and purpose is to make sure powertrain, chassis and electrical systems all have the same voltage reference to the battery and each other.
1. Battery neg to engine block
2. Batt neg to chassis frame
3. Engine block to chassis - usually firewall, but shortest route otherwise, and not same as battery to chassis.
All wiring harness grounding points are critical. If it doesnt happen anymore then that was it.
Besides that, to rule out possibilities of problems more difficult to solve than that one..
All vehicles should have three grounding cables:
- NOT counting harness grounding points. These are discrete wires and purpose is to make sure powertrain, chassis and electrical systems all have the same voltage reference to the battery and each other.
1. Battery neg to engine block
2. Batt neg to chassis frame
3. Engine block to chassis - usually firewall, but shortest route otherwise, and not same as battery to chassis.
Last edited by pettyfog; 10-22-2011 at 01:38 PM.
#4
10-23-2011, 08:53 AM
All vehicles should have three grounding cables:
- NOT counting harness grounding points. These are discrete wires and purpose is to make sure powertrain, chassis and electrical systems all have the same voltage reference to the battery and each other.
1. Battery neg to engine block
2. Batt neg to chassis frame
3. Engine block to chassis - usually firewall, but shortest route otherwise, and not same as battery to chassis.
- NOT counting harness grounding points. These are discrete wires and purpose is to make sure powertrain, chassis and electrical systems all have the same voltage reference to the battery and each other.
1. Battery neg to engine block
2. Batt neg to chassis frame
3. Engine block to chassis - usually firewall, but shortest route otherwise, and not same as battery to chassis.
- Way long time ago I helped out a friend whose engine ended up being grounded through the exhaust.. he wondered why it started fine one time, not the next.. and why his AM radio had nothing but static.. really ignition and alternator noise. Found he moved his big ground wire to engine mount bolt to get it out of the way, crossmember side, of course.
The statement stands and anyone who's had weird electrical problems will back that up. Of course SOMETIMES that will lead to difficulty in troubleshooting problems of it's own but if all three are well fastened and clean connections, you wont have any problems attributed to phantom electrical currents.
You do have to make sure the wire to terminal connection is good as well.
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