Weird Electrical Problem

[skokie]

Ok I have installed a new under dash wiring harness that I bought from M&H. Here is the problem. I dont have any brake lights, When I turn on the parking lights the high beam light comes on, when I turn on the headlights the beam light acts normal & the blinker lights are on solid. Also replaced the board on the back of the dash. Also if I leave the battery cables on the battery it goes dead.
Anyone ever seen this stuff act like this?

Thanks

[ChevLoRay]

Sounds like you installed a few gremlins, too.

Although it ain't going to be easy, the only real option you have is to take the installation instructions, and a wiring diagram, and re-check everything. In all liklihood, one (or more) wires are swapped, not connected to anything, or shorted together. Bad grounds can wreak havoc, too.

[skokie]

Yep thats what I was planning on doing. I am going through the assembly manual and the service manual looking for the diagrams for the fuse box and everything that connects to it. Something I didn't mention was that before everything worked fine minus the fact that the wiring looked like a hungry squirrel had been under their munching away. Also I just remembered that I dont have the ground straps from the motor to the firewall re installed. Could that be part of the problem?

[clay68c10]

I'd re-install your grounds before you get any further, it may be a problem and is definitely an easier fix than tracing wiring.

[Musclerodz]

sounds like some wires are swapped somewhere.

Mike

[skokie]

I re did my grounds. By redid I mean I took a wirewheel and went to bare metal and then installed the grounds that I moved. Same issue. Left blinker activates the right rear blinker.

[Longhorn Man]

were any of these problems there before you replaced this harness? You may be blaming a new part that has nothing to do with the problems. They seem unrelated to me for the best part.

[skokie]

Everything was working fine before I installed the new parts. Only reason I replaced the under dash harness was because it was a fire hazard. The under the hood harness was replaced abut 18 months ago and had 0 issues.

[skokie]

Think I will take out the harness and get into the garage to have a better look at it just to make sure there are no bad connections.

[skokie]

I had a quick look tonight at the harness and compared it to the old one that came out of the truck. They match up except for the differences between a 3spd and auto .Truck was converted to an auto before I bought it but wiring was never changed over. I called M&H wiring and left a voicemail so I should hear back on Monday. ! step forward 3 steps bacl

[skokie]

Ok for the heck of it I took out the old column and hooked it up to the new harness to see if it was a issue with the turn signal switch. Same issue. No change. Its got to be something in the wiring and if it wasnt raining I would rip out the new one and hook up the old one just to find out.

[Boog]

Skoke. In your build thread you state you pinched an under hood wire bad enough you now have a short. Was that with the new in cab harness in place? You may have two or more wires melted together somewhere between that pinched spot and the light switch.

[skokie]

Originally Posted by Boog

Skoke. In your build thread you state you pinched an under hood wire bad enough you now have a short. Was that with the new in cab harness in place? You may have two or more wires melted together somewhere between that pinched spot and the light switch.

That harness was replaced a few weeks after I posted that and the new underdash harness was installed afterwards.

[Boog]

Ah, it's gonna turn out to be something really simple and you're gonna be like 'DOH! The M&H people may can offer some help on Monday.

[skokie]

Originally Posted by Boog

Ah, it's gonna turn out to be something really simple and you're gonna be like 'DOH! The M&H people may can offer some help on Monday.

LOL you are probably right. This crap always happens to me in just about everything I work on. Oh well its not going to stop me. I was a network engineer for 7 1/2 years and saw this crap all the time hahahahaha

[earl87gta]

Did the new harness replace the ignition switch my blazer was doing similar things and it ended up being the ignition switch that was causing it. The connector was jacked up I ended up replacing the connector and the switch to fix it. Only reason I found out it was the trouble was it eventually started to get hot enough to burn I would never had thought it was causing my blinkers and tail lights to act crazy.

[skokie]

Ignition switch was replaced as well. OK i talked to M&H tech support today. We went over the wires at the U connector and they are correct however he suspects that they may be crossed at the bulkhead which I did not check. I will be doing that tonight. Once that is covered then we will tackle the brake light problem. More to come.

[ChevLoRay]

Originally Posted by Boog

Ah, it's gonna turn out to be something really simple and you're gonna be like 'DOH! The M&H people may can offer some help on Monday.

It's always easier to think that the new part has a problem and there is NO WAY that I could have done anything to screw it up. Geeze....is there no end to this crap?

Hope you get it all worked out without too much "disassembly".

[skokie]

Ok here is the latest. I got home today and called M&H. While I was on the phone I removed the harness from the cabside and under the hood. Then I took the cover off of the back of the harness and we went through each wire and they all matched up to what M&H has. I grabbed my old harness and checked against that and it matched up as well. I then reinstalled everything just like I did on Sunday.

With the new tilt column plugged into the U connector same stuff. No workie. I plugged in my old columns blinker switch and IT WORKED!!!!! I went through a entire light check everything worked as it should. M&H asked if I had a multimeter and I said yes so I got it out and checked in the u connector on the green, white and yellow wire. Had 12 Volts each time. Plugged in the new tilt and only got 12 Volts on the green. Nothing on the white or yellow.

What gets me is why didnt the old column work before I took it all apart and put it back together? So I got a new turn signal switch on the way. Since that is fixed I am back to work on the truck. Going to try to get the inner fenders installed tonight.

[skokie]

Forgot to add that also my reverse lights are not working. Going to tackle that one tomorrow.