Ground problem?

['70GMCStep]

Have got a little electrical problem. Took some time today to install receiver hitch on the truck. Went well. Drove it later and I had no lights in the rear, no dash lights, dome light and no turn signals or brake lights. Also had a little burn smell under the dash and a warm wire when light switch was on (although I did not when light switch was off). I did have headlights on when back at the shop, but none of the other.

Did I mess something up with a ground somewhere? Had to take some harness connector ties off of frame to get receiver in, but other than that....

Was so up on getting receiver in, but bummed about this. By the way, I did not install the trailer harness yet, so nothing was done there, yet. Ground problem somewhere? I know this is probably simple, but my knowledge of electrical is...also simple.


'70GMCStep

'70 GMC Stepside swb
'65 Chevy C-10 lwb, bbw

[Max1775]

If you have a burning smell under the dash and a burnt wire, sounds like something is shorted. Are all the fuses still good?
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['70GMCStep]

I'm not sure yet. I think I'm going to start at the fuse box tomorrow and work. I really need to replace the under the dash wiring, but will when wife gives the ok. Never found the burnt wire, but thought for a moment that it was the welding smell from having to modify my harness a bit. Also not sure that I unhooked the battery before the final bit of welding took place.

[vin63]

Originally Posted by Max1775

If you have a burning smell under the dash and a burnt wire, sounds like something is shorted. Are all the fuses still good?
Posted via Mobile Device

X2...it may have just been a coincidence that the wire shorted right after you installed the hitch. But, it might be worth tracing back the rear tail light harness just in case there is/are damaged or exposed wires, etc.

[kieth]

Check your main grounds up front, the one from the battery to the block, the one from the block to the frame the one from the body to the frame, the high amp load from the welder can burn out those light Duty grounds ....you should always disconnect the battery when welding and the alternator, if your welder cannot find a good ground it will make its own ground thru anything available and of course overload it.......Kieth

[Longhorn Man]

forget the grounds.
Go back and look to see if you pinched a wire when installing the hitch.
Your dash lights, brake lights, parking lights, and dome light are all on one fuse. The turn signals are on another one. If you didn't pinch anything, then inspect the harness back there, since you were just working there before the problem came up.

['70GMCStep]

Here's what I found. A burnt out fuse, but replaced it. While checking lights, the wires got warm again and the smell, but still nothing more than I had last night. Checked grounds and all, checked the wiring to the back. Looks like I'm starting from scratch. Looks like a good time to replace under dash wiring that looks terrible anyway with the half melted wire I found.



Thanks for the advice,

'70GMCStep


'70 GMC Stepside swb
'65 Chevy C-10 lwb bbw

[fixit-p]

Originally Posted by Longhorn Man

forget the grounds.
Go back and look to see if you pinched a wire when installing the hitch.
Your dash lights, brake lights, parking lights, and dome light are all on one fuse. The turn signals are on another one. If you didn't pinch anything, then inspect the harness back there, since you were just working there before the problem came up.

Right there what LHM said, bad grounds wont cause your problem, replacing the under dash wiring before fixing the problem is just going to put your new wiring at risk, first check that there are no wires pinched at the hitch. A short circuit will cause the fuse to blow but not necessarily cause the wire to get hot unless the wrong size fuse is installed or you have excessive resistance in the wiring causing a voltage drop (heat).

['70GMCStep]

Yea, I messed up big on this. Getting a new harness would be another mess up. No pinching anywhere on back end. With all of the cylinder shaped fuses, does anybody know which model or size to be used. I mean I fit a new one in last night, but it didn't "feel" right. I just usually buy a pack, the "buss" fuses.


Thanks,
'70GMCStep

[VetteVet]

You may have shorted one of the tail light or turn signal wires when you installed the receiver hitch. you do have a ground problem but it's a short to ground. Disconnect the wiring connector to the rear harness at the plug in the firewall just to the left of the distributor. This will isolate the rear end from the cab and then check for the burning smell and hot wires. If you don't have the symptoms as before then the problem is in the tail light harness. If you still do then it's in the cab and you should have a blown tail stop fuse in the fuse panel. It may have already blown so you will have to replace it to check for the short.

What the other guys said applies as well.

[john_p]

have to agree, you are pinching a wire.. depending on which fuse your blowing.. i saw a similar problem where everything worked perfect until the break lights tried to come on.. all lamps died. your getting a hot wire back to frame ground some where.

['70GMCStep]

Ok, its got to be the rear wiring harness back from the cab that is bad. Put a ground thread assembly on to replace the ground wire that was on the truck, not sure if it was needing it, but did it. Then put on new fuse, but it of course blew.
Need to find a 10 amp fuse like the wiring manual mentioned, but I think a new rear harness is in the future. No warm wire no smell though and all electrics working from cab forward. This dude hates electrics but have to have them...


'70GMCStep