New harness, gauges just started to work?!?

[mrmolding]

Not sure if this sounds obvious, but I installed all new m&h harnesses, new Oer gauges, new repro rallye circuit board, solid state limiter (5 years old), new fuses, new voltage regulator, ballast resistor, new ignition switch, nos signal switch, all mechanical switches in dash are restored.
What is not new is alternator and battery. Yesterday after 6 months of resto I decided to start it up.
So, the lights came on, alternator gauge worked, hazard switch worked, park lamps and brake lights worked.
Other than that, nothing else worked — turn signals, fuel, tach, temp all did not work. So I called it a day.
Today I spent two hours with a multimeter checking continuity all over the place and everything seemed ok. Then I remember reading a post about turn signals not working unless radio was connected. So I did that and still nothing worked when car was started.
So…then I put back in original turn signal flasher and removed led flasher after trying different polarization based on other posts. The rear bulbs are led so I figured I needed a led flasher. Still no luck.
So then I decided to move on to something else, and I let car get to temp and check thermostat. After idling for about a minute, I brought Rpms up and all the gauges came on! Turn signals worked, wipers worked, etc. I did not hear a pop or anything when it came on, just wondering if this is very obvious to anyone as to my luck!
I have since started and turned off car a few times and everything still works.

 

[pnora]

Time bomb. You did not find or fix it so it will come back. You never said what year. If all new I suspect something not fully plugged in . And the radio not plugged in forget that wacko idea.

 

[mrmolding]

It’s a 70. Thanks!

 

[pnora]

It’s a 70. Thanks!

Being a 70 double check the steering column connectors.

 

[Builderguy]

Agree with pnora above. Something was not making contact. Could be just about any of your connections but since several items were affected, I would suspect a ground is loose.

 

[mrmolding]

Ground makes sense. I touched back of gauge cluster and different parts of steering column with multimeter and got continuity. I’ll keep looking. But nothing jumps out like faulty alternator, voltage regulator?
Also does it make sense to run a separate ground from battery and run wires to a new bolt termination under dash? My neighbor builds engines and recommended that. The purist in me is not sure!

 

[pnora]

Ground makes sense. I touched back of gauge cluster and different parts of steering column with multimeter and got continuity. I’ll keep looking. But nothing jumps out like faulty alternator, voltage regulator?
Also does it make sense to run a separate ground from battery and run wires to a new bolt termination under dash? My neighbor builds engines and recommended that. The purist in me is not sure!

Ground does not make sense. What does not work is all keyed 12 volt fed circuits.

 

[Builderguy]

I am not sure of the exact part number for a 1970 ground cable but I believe it is like this where the second wire grounds to the radiator support.

 

[mrmolding]

I am not sure of the exact part number for a 1970 ground cable but I believe it is like this where the second wire grounds to the radiator support. Not sure if that would cause issues

View attachment 1229418

I have that cable. My neighbor suggested to run a third ground from core support through bulkhead and connect to new bolt under dash — then run led flasher ground and anything else with issues to that such as back of dash cluster. Not sure if another ground makes sense.

 

[Builderguy]

I guess I would just do what was done to 73's & 74's and run a braided ground strap from the back of the block to the firewall. Then anything bolted to firewall will be grounded a little better. Your way would work so it is up to you. Before making any new holes you may want to run a temporary ground wire to the "led flasher ground and anything else with issues" and make sure it solves your problem. I have mixed LED's and stock bulbs on a couple of occasions but have never had good luck doing that and had to add a resistor to make everything work.

 

[Builderguy]

If I remember the rear lights needed this
Important note regarding indicator bulb

Replacing your indicator bulbs is much the same process as any other light on your vehicle, but with one important difference. Your car’s indicator wiring circuit has been set up for incandescent light bulbs which offer a particular amount of resistance. In comparison, LED lights offer little electrical resistance – and in layman’s terms this means your car’s indicators may “hyper flash” (flash very quickly) if you replace all the bulbs with LED’s.

In order to fix this, you must either purchase LED bulbs which are advertised as having the correct amount of resistance built in, or you’ll need to purchase separate resistor units which must be spliced into the wiring circuit to slow the flashing back down to the normal speed. This is obviously a more involved process, so if you aren’t confident with the job I certainly wouldn’t tackle it yourself without doing some research first and having the necessary tools.

 

[mrmolding]

If I remember the rear lights needed this
Important note regarding indicator bulb

View attachment 1229437

Replacing your indicator bulbs is much the same process as any other light on your vehicle, but with one important difference. Your car’s indicator wiring circuit has been set up for incandescent light bulbs which offer a particular amount of resistance. In comparison, LED lights offer little electrical resistance – and in layman’s terms this means your car’s indicators may “hyper flash” (flash very quickly) if you replace all the bulbs with LED’s.

In order to fix this, you must either purchase LED bulbs which are advertised as having the correct amount of resistance built in, or you’ll need to purchase separate resistor units which must be spliced into the wiring circuit to slow the flashing back down to the normal speed. This is obviously a more involved process, so if you aren’t confident with the job I certainly wouldn’t tackle it yourself without doing some research first and having the necessary tools.

Thanks for the help! The led bulbs were put in by the PO and I like them. I called mfr and they said I needed an LED flasher but they work with stock flashers anyway. Your info helps greatly!

Now I do like the idea of running a new ground post but my original issue of everything just starting to work when I loosened or moved nothing has me stumped! Problem is still not solved since tach is still not working. I’ll keep plodding along.

 

[Jc cooper]

This may not help, but verify each wire , plugged in at the bulkhead connectors , that each wire is approximately crimped to the end and also verify, that when you plugged the connectors to the bulkhead block that each wire actually made a correct connection! Been there and saw a problem here ! Never assume anything with anyone’s after market parts or harnesses , even though your brand is recognized as good ! FME , usually it’s a very minor thing that creates issues ! Just my opinion of course!

 

[mrmolding]

So a possible update, I went through and checked everything, retightened, connectors and got tach to work. It was fine for two days. Putting key to accessory? (right before start) the radio comes on, turn signals work and all good. Today I got in and put key to same position before it cranks and nothing comes on again!
So, I recheck things again but realize that I have one of the battery connection disconnects. I wonder if that is what keeps changing since I disconnect it every night. What is best way to check voltage once I reconnect this thing or am I off?

 

[pnora]

So a possible update, I went through and checked everything, retightened, connectors and got tach to work. It was fine for two days. Putting key to accessory? (right before start) the radio comes on, turn signals work and all good. Today I got in and put key to same position before it cranks and nothing comes on again!
So, I recheck things again but realize that I have one of the battery connection disconnects. I wonder if that is what keeps changing since I disconnect it every night. What is best way to check voltage once I reconnect this thing or am I off?

View attachment 1232197

It will not affect anything unless it is not making a good connection when reconnecting it. Easy enough to diagnose when it is acting up with a voltmeter.

 

[pnora]

Why not just remove it and clean the cable end and battery terminal. Try it that way for a while. I had a job on a guys plow truck that used one of those disconnects. It ended up being the problem.

 

[mrmolding]

Why not just remove it and clean the cable end and battery terminal. Try it that way for a while. I had a job on a guys plow truck that used one of those disconnects. It ended up being the problem.

Been wondering if it is the voltage limiter. I’ll report back after the next round of tests. Thanks again!

 

[Jc cooper]

Kiss , keep it simple, verify the grd cable is not the issue, as recently stated in another post! Ground cable not sufficiently connected, can produce some strange happening!

 

[mrmolding]

Kiss , keep it simple, verify the grd cable is not the issue, as recently stated in another post! Ground cable not sufficiently connected, can produce some strange happening!

Thanks! That is first and I actually have a new cable. If the problem comes back without the battery saver, I’ll keep looking.

 

[Jc cooper]

Sounds good!