What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Electrical short

U

Ukjimmyfan

Registered Member
Joined
Jan 31, 2025
Posts
21
Reaction score
2
Location
UK
Hi,
After the truck (1982 GMC JIMMY 6.2, stock) shuddered—axle tramp from full throttle - the electrical system has gone haywire.
1)no wipers
2)wiper switch on, indicators on.
Seat belt warning lamp on, ammeter flicks in time with indicator. Engine temperature gage sinks down.
3)dash lights never worked anytime /live to dome interior lamp poor- again probably years old issue.
Wiper motor checked out OK.
Nothing visible in dash wiring loose or detached. Or engine bay.
Wiper switch on dash with plug in intermittent box.
Where next please?
 
Check grounds. There is a big black wire from one of your batteries that should go to the frame. There should be a smaller black wire going to the body. Make sure that wire is still connected, remove the bolts on both ground wires, clean everything and bolt them back up.

Also, follow the parking brake pedal up to its mount. At the top of the mount is a 6 or 8 pronged plug bolted to the mount. All of the ground wires for inside the cab go to this. Remove the 6 or 8 pronged retaining bolt, clean everything and put it back together. Hopefully that fixes it. If not, it will be a common fault preventatively prevented.
 
Sounds like a short between the driver's seat and the steering wheel :D

Seriously though, check all the ground connections.
 
If you're able to rip a ground strap or wire with the throttle, it's time to check the engine mounts.
 
It does dound very much like a ground issue. Negative Earth in UK. Is this truck right or left hand drive?

Main ground negative battery to engine, clean unpainted block, away from exhaust heat.
Second and thrid battery negative to frame 10 ga conductor, and radiator core support.
Fourth ground from intake manifold/rocker cover to firewall/bulkhead.
At the radiator core support above each headlamp there will be a ground for there. This is for lighting.
In the cab above the parking brake pedal mechanism will be a bus bar with several tabs lookfor more gronds there. These will be for your instrument cluster and lighting.

2 nations separated by a common language
 
Hi, thank you all for the pointers.
The engine bay I regrounded using thick arc welding cable.
The others I will go through as you suggested.
It is normal left hand drive not one of those dodgy conversion jobs.
However the wiring loom is chopped about for the local lighting regulations.
I am hoping not to strip any more of the dash. The plastic foil for the back of the guages is a nightmare I don't want to change.
Seems not much difference in quality between 70ies Italian car electrics and this.
It was found in a yard and one bulb worked on the whole truck. After sorting it putting it back on the highway I'm loosing interest...
 
I'd fit some traction bars if I can get some.
Might be able to make something from a pattern???
Axle tramp/tire hop is usual with leaf springs. I suppose buying a corvette is the cure. or wait for 20mph then full gas.
 
Ukjimmyfan said:
I'd fit some traction bars if I can get some.
Might be able to make something from a pattern???
Axle tramp/tire hop is usual with leaf springs. I suppose buying a corvette is the cure. or wait for 20mph then full gas.
Click to expand...

There shouldn't be any axle tramp, especially with a 6.2L. Something is amiss.
 
Last edited:
Yeah that is a puzzle to me to.

Maybe with small diameter tires.
could be loose u bolts, bad eye bushings, ysed up or broken leaf spring.

bad pinion bearings some time sound or feel like axle hop ir tramp. has anyone watched the rear axle while tramp is occurring?
 
I looked in the engine bay. Alongside the auto gearbox shifter mechanism/bulkhead is a wide flat cable with 4 wires inside in a row. 2 green, yellow and a dark brown (black?) .
It seems to have some sort of a bare spade connector along it
There is no obvious place to reattach it to.
Was there something on the column etc it went to?
Ps sorry this phone won't do pics.
 
Ukjimmyfan said:
I looked in the engine bay. Alongside the auto gearbox shifter mechanism/bulkhead is a wide flat cable with 4 wires inside in a row. 2 green, yellow and a dark brown (black?) .
It seems to have some sort of a bare spade connector along it
There is no obvious place to reattach it to.
Was there something on the column etc it went to?
Ps sorry this phone won't do pics.
Click to expand...
That's for the rear lights.
Brown is tail lights, yellow and dark green are turn signals, light green is reverse
 
Thanks for the advice both of you.
I will find out.
There were no loose earth's I could see in the cab.
An auto electrian would want $500 to find the fault, if they would touch it the state it's in after previous chimps have left/modified it.
So I use that cash to hopefully bypass the short and build a new wiper system with a wrangler YJ wiper motor, universal switch and bosch style relay.
At least the parts are cheap/available unlike the OE stuff.
Not $700 like the holley upgrade nice tho it looks.
Well a PO had added a toggle switch and expanding foam around the rack causing damage.
I will roadtest it when I get time.
 
You must log in or register to reply here.

Latest Posts

Top Bottom