Wiring Disaster-Please Help

[hotrodmtodd]

Will try to keep this as short I can. 72 Chevy, not going to say what model so that the well meaning mods wont transfer this somewhere that no one will see it. Have headlights, high and low beams. Have running lights and interior lights most of the time. Have no turn signals and no hazard lights at least not this moment, 5 minutes from now that could change back. Have brake lights until they decide not to work again. Heres what I have replaced, everything. New headlight switch twice, new dimmer switch, new brake light switch and new turn signal switch. New heavy duty flashers. I have jiggled every single wire I can touch to see if anything blinks. This sure seams like some kind of ground issue, but I cannot duplicate it sitting still. When I drive and bounce around, take your pick at what might work at that moment. Could this be a ground strap or steering coupler problem? This is one of my favorite trucks, so junking it is not an alternative. Somebody PLEASE try to give me some idea where to start with this. I hope the fact that I am desperate is evident. Thanks, Mike

[usmcchevy]

Lets see, on a 72 Blazer I would start by checking the grounds between the frame and cab (tub) and also battery and frame/engine. So to answer your questions. Yes, this could be a ground problem. No, I highly doubt there is a problem is in the steering column.

[stsalvage]

Most people don't understand the more grounds you have the better you are.So i would start putting more grounds all over your truck It can't hurt

[cdowns]

the ground path starts at the light bulb and you must b able to trace it from the light bulb all the way to the battery for electricity to flow properly// it aint just wires of cables that create a ground

[70GMCBB]

Probably ground but I had a strange problem similar once. Chased and chased it. Come to find out the trailer light plug in the rear bumper had an insert in it. This was held in with a set screw. The set screw had come out and the insert would vibrate back and forth in the housing occasionally shorting out on the flap on the outside. It would blow fuses now and again though. Finally tracked it down. Put a new set screw in problem solved.

[1972RedNeck]

My strap from frame to body was broke on mine.

[68gmsee]

Originally Posted by cdowns

.........it aint just wires of cables that create a ground

Sactly! Years of road grime and rust have reduced the ground path between frame and cab to the battery. Some of the lights use this frame ground to create the path to neg on the battery.

I eliminated several gremlins by adding ground cables from bed to frame, frame to cab and cab to engine. I even added an additional one to radiator support.

[JORGIE95961]

Highbeam switch was my problem

[daveo68]

Had one, took three days to track down. Ground wire on one of the tail light assemblys was cut through insulation. It is aggravating sometimes trying to find grounds

[hotrodmtodd]

Thanks guys for all the input. Drove it again today. Had parking lights when I left, they were off within a few miles. Turn signal indicators only come on when I hit the brakes. I have never blown a fuse or shorted anything out that I know of. Have never smelled anything burning. Please give me some troubleshooting tips if you can. I assume all these switches are all connected to each other in some way. I just need to know what to put a test light on to check things. How do you check for grounds? I used to have a list of all the ground straps on these trucks, but cant remember where I put it. If someone could give me that again it would help. Thanks again, Mike

[70GMCBB]

Make sure your negative battery cable ties directly to the engine block. I've seen it connected to an accessory bracket and sometimes directly to a head. If I remember correctly there is a ground strap on the back of each head connected to the frame. I've also seen a smaller wire from the negative battery cable at the battery going to the frame. This is a start anyway. I'm not sure but there might be ground straps at the back tail lights also.

[dcasalena]

Originally Posted by 70GMCBB

Make sure your negative battery cable ties directly to the engine block. I've seen it connected to an accessory bracket and sometimes directly to a head. If I remember correctly there is a ground strap on the back of each head connected to the frame. I've also seen a smaller wire from the negative battery cable at the battery going to the frame. This is a start anyway. I'm not sure but there might be ground straps at the back tail lights also.

pretty sure the only ground wires at the back are on the side markers.
tails and reverse ground through the metal light bracket thingies.

[68gmsee]

No need to be specific as to where the grounds go as long as they complete a loop to the negative battery terminal.

As for measuring the ground, it will be somewhat difficult since these trucks use the frame, cab, engine as a source as -mentioned previously.

Here's what I did:

Made sure I had a new ground cable from the battery to the engine. These can go bad at the battery post connector and you won't be able to see it. Then I got some ground straps at the local auto parts stores.

1. Placed a strap from rear bed support to the frame. Doesn't matter where but you may have to drill some holes on the frame and bed support. I used self tapping bolts and sheet metal screws.

2. Placed another under the cab to the frame.

3. Made sure I had a nice clean connection on the one in the rear of the engine to the cab.

4. I added an additional one from the radiator support to the battery negative post. Didn't trust the old bolts.

[jaros44sr]

Hows the condition of theground strap under the passenger side seat, down at the frame. How about checking the rag joint in the steering column.

I would give you more ideas if you posted up some pics of the pop up camper

[hotrodmtodd]

Thanks to everybody that chimed in here. I am going to check/replace them all til something works. Take care, Mike


Hehe. Thanks Jim, I do have some pictures of the Blazer with the camper on it somewhere. They were taken by Craig (cool guy from TN I think with a nice maroon Blazer, cant remember his screen name off hand) at the 07 National board meet at Bosses house. Will try to dig those up and send them to you one of theses days

[dammitmitchell]

Originally Posted by hotrodmtodd

Could this be a ground strap or steering coupler problem? This is one of my favorite trucks, so junking it is not an alternative. Somebody PLEASE try to give me some idea where to start with this. I hope the fact that I am desperate is evident. Thanks, Mike

SCRAP A TRUCK BECAUSE OF ELECTRICAL HELLLLLSSSS NO..

to me if all that is intermittent it definatley sounds like a grounding issue.. start at either tue fuze block or the steering colum/dach connectors. CLEAN and scrubb off every connector with electrical contact cleaner.

also make sure the chassis is grounded to the frame and battery.
i typically make a "master junction" spot on the frame where the battery negative, body grnd, and engine grnd are all in the same spot. but i also have backup grounds floating everywhere.


so.. scrub clean and start over brother it's out there. It is just going to take time.