Rewiring a 67' coupe

[Tim801]

Hi everyone,
My 67' coupe wiring caught on fire near the headlight wiring harness. Should I buy the painless wiring kit and do it myself or should I take it to someone to have it done? How hard is it with the painless kit?

 

[Horseplay]

Why not just buy a replacement harness for the affected area? Plug it in and go. Be a hell of a lot cheaper and easier. Of course, make sure to understand why the first wiring failed before powering things up.

 

[David67]

First you need to figure out how far back the wires burned up. If it stopped there just replace the engine bay harness. It will be just plug and play. That's sucks man!!!

Sent from my SCH-I535 using Tapatalk 4

 

[cmayna]

Tim, hopefully Midlife, our house electrical guru will chime in with more ideas.

 

[Midlife]

I refrained from offering my services, less I be accused of shilling. Unless there are other requirements/modifications, a refurbished or reproduction headlight harness is the most cost-effective solution.

 

[Tim801]

The wiring everywhere else in the engine bay looks fine. It's just the connection in the picture that is burned up. The car has never been rewired in since I've had it and it sat for 19 years before hand..would you guys rewire the entire car or just sections as needed like the engine bay? I've been really busy at work this past week. Ill take some more pictures of it tomorrow and post them up. Midlife, maybe ill buy the replacement headlight harness and then go from there. What would your guess be to why the fire started?
Thanks,
Tim

 

[Midlife]

I can't tell whether the short is on the passenger or driver's side.

 

[cmayna]

Das, duh passenger side, standing in front looking into the engine bay.

 

[68EFIvert]

I am going to rewire my car with an American Auto Wire Harness. My view is that if part of your harness burns up what does the rest look like? If it were me I would rewire the entire car. It doesn't seem to be that hard to wire the car, just time consuming. I expect to spend about 40 hours to do the job. Midlife can rework you harness and provide a great product. I did not go that path because of all the extras I have on my car like power windows, larger stereo, EFI... that will all add to the load of the electrical system. If you don't have all that crap and don't expect to add it Mid is your man.

 

[Midlife]

Most shorts in that area of the wiring harness usually are from the harness coming in contact with the headers. For a 1967, most of the wiring routes through the radiator support to the starter solenoid, so the only thing left over there is the starter cable. The other possibility is that the wiring is part of the alternator harness; it can get caught in rotating parts and cause a short that way.

A more detailed failure analysis can be conducted once I can examine the wires in person. For me, trying to determine how wiring fails is the most interesting aspect of harness refurbishment. I rarely see 67 issues on that side of the engine. 1970's, however, are very prone to failure/shorts along the passenger side shock tower, as they are not supported out of the way of the hot headers.

 

[Horseplay]

I am going to rewire my car with an American Auto Wire Harness. My view is that if part of your harness burns up what does the rest look like?

I spent a good amount of time playing around with my wiring deciding which way to go myself. What I found was that the under hood harness(es) were by far in much worse shape than those in the cabin/trunk. Those front pieces are subjected to harsh environmental conditions and most likely the greater detrimental cause...engine heat.

The only issues I found with any cabin wiring was corrosion at spots like firewall connectors and the back of the fuse block. The wiring itself was still very soft and bendable, etc. The wires under the hood...not so much. Dash wiring, aside from being a bit dusty and maybe a little faded was really quite good.

I ended up using all new harness reproductions and my original dash harness. Then I did some serious modification from there to accommodate all the new power accessories and such I am/have added to the car. I also incorporated a new modern fuse block to gain extra fused circuits and facilitate the use of modern automotive fuses.

 

[68EFIvert]

I am also using an auxiliary fuse panel from Painless for all my new stuff but I am having a short problem that is driving me nuts. I can't find it and lost my patience. For me one fuse panel with new wires to everything is the best solution. Now if I didn't have any wiring problems currently I wouldn't care and wouldn't be going through the expense and hassle of a rewire. This is the final bug to work out on my car and then it is done...... I think.


Darreld
Sent from my iPhone using Tapatalk

 

[Midlife]

I am also using an auxiliary fuse panel from Painless for all my new stuff but I am having a short problem that is driving me nuts. I can't find it and lost my patience. For me one fuse panel with new wires to everything is the best solution. Now if I didn't have any wiring problems currently I wouldn't care and wouldn't be going through the expense and hassle of a rewire. This is the final bug to work out on my car and then it is done...... I think.


Darreld
Sent from my iPhone using Tapatalk

Here's my standard recommendations for finding shorts and excessive current draws:

_________________________
First, always install electrical wiring with the battery disconnected.

Physically install the underdash harness with fuses. Connect all underhood and taillight harnesses.

When ready to check out the harness, close all doors, turn off all lights, ignition key in the OFF position, accessories off, etc. Make sure both battery connectors are disconnected. Connect the positive battery cable to the starter solenoid. Leave the negative terminal disconnected from the battery. Then use a digital volt meter to measure the current draw across the battery. Place one probe of the DVM on the negative battery cable terminal, and the other probe on the negative battery post. Be sure that the DVM is set to amps, DC. If there are no shorts in the wiring connections, the reading should be on the order of 30 milliamps or less. Anything above 1 amp indicates some accessory is on; readings above 10 amps (may blow the fuse on the DVM) indicates a dead short.

If you have a short, disconnect all other wiring from the starter solenoid post where the battery connects and re-measure the current. If current drops, the source is the underdash wiring harness or the harness from the starter solenoid to the firewall. Reconnect the wiring to the starter post and then disconnect the underhood harness from the firewall and test again to isolate the source of the short.

If the short is not in the underhood or underdash harness, the problem lies in the alternator or voltage regulator. Disconnect each of these in turn to isolate the source.

If the short or high current comes from the underdash region, keep the battery negative side disconnected and remove one fuse at a time. Measure the current as above. If you now see low current, there is either a short or an item on that particular fuse circuit is on. Turn off that item and continue checking.

Eventually, you’ll have low current readings with all fuses installed and all wiring connected. This series of tests checks all of the battery directly powered systems. To check the Accessory systems, now repeat all of the tests above with the ignition key in the ACC position. The current with the key in the ACC position may be up to 1 amp or so. When all of the tests are done and no anomalous current is noted, at that time, and only at that time, is it safe to connect the negative battery cable to the battery.

 

[68EFIvert]

Thanks for the step by step instructions Mid. I went through it last night am a little more cofused than I was before. I started out disconnecting the negative side of the battery. I then went to the solenoid and unhooked everything off the solenoid post the positive battery cable connects to. I had a draw of 2.8 amps. I then hooked all of the items back up to that post and it stayed at 2.8 amps. I repeated removing all items off the different posts of the solenoid and it had the same amperage draw. I then felt if must be inside the car.

I started pulling fuses one by one from my new Painless buse block and the draw stayed the same. I then moved to the original fuse panel and it did not change there. I then remembered that I had some stereo items hooked directly to the battery and disconnected everythign from it. Still not change in the draw rate of 2.8 amps. I am perplexed now. Not sure where to troubleshoot from here. Did I do it incorrectly? I still haven't looked at anything with the key turned to ACC.

Sorry to hijack the thread.

 

[Midlife]

Remove everything from the battery solenoid post except the battery; remove all other wires from the other posts. Measure current; it should be zero or very close to it. If not, then the solenoid itself is bad. If zero, attach the other wires to the solenoid one by one, measuring current every time you add a wire.

 

[68EFIvert]

Thanks Midlife! I never thought it could be my new solenoid. I will follow your instructions tonight.