Instruments going to far right side - 66 Sat??

[RemCharger]

I believe the output from the 5v reg should show 0-7v in a sq wave as mentioned. A test light should blink dimly on and off.

 

[AR67GTX]

Testing:

At battery at idle - 12.6V +/-
At battery engine reved up - 14.2V +/-

Alternator reads steady at idle and steadily increases as I give the engine throttle and then as it nears the upper end of the gage it starts jumping back and forth from near 0 to near high area.

I had another old instrument voltage regulator I found on a cluster I pulled out of a junkyard about 20 years ago so I plugged it in but nothing changed. Gauges would still peg to right after a couple minutes and then fall back when shut down. I did get my ear down and could hear the regulator clicking away like mad when I reved the motor.

Pulled plug off of coolant sender unit and gage stayed pegged to the right.

Hooked a ground lead up from the instrument cluster to the chassis - no change.

Took my meter and clipped to a ground and clipped the red lead to the power side, threaded stud on the back of the temp and then the gas gauge.
At idle - 6.7V
At revs - 7 - 8V, some peaks around 9V

And this is the kicker - turned key off and still had 6.4 V at gages??

The car has a new engine harness but I'm suspecting I have a dash harness issue or a printed circuit sheet on the back of the cluster that is leaking voltage over.

 

[65-440]

Pulled plug off of coolant sender unit and gage stayed pegged to the right.
.

That's not good, with no ground signal from the sending unit the gauge should not move....sounds like it's time to do some wire tracing.

 

[AR67GTX]

That was kind of my sentiment too - not good. The ignition key circuit feeding the gages/voltage regulator power has a splice in it and also feeds the flasher and the fuse to the radio. Guess I’ll see if the are showing any voltage on them with the key off but more probably leaking over from lighting switch somehow.

 

[AR67GTX]

I may have found the problem. Started out at the alternator/coolant sensor plug (this is a Hemi car) on the valve cover and saw signs of melting of the connectors. Sure enough they would not come apart and basically destroyed both plugs getting them apart. I suspect the alternator lead was shorting over to the coolant temp sensor lead - hard to tell.

So looks like a new engine harness too probably. Any thoughts on what went on here? I haven't pulled the alternator yet but I've noticed some funky wiring from the back to the front case like it's a dual field alternator and they grounded the extra field terminal? But it looks like a standard single field alternator outwardly. Maybe you can't tell from outward appearance.

I'm probably going to want to move this car over in my garage to get it out of the way for awhile and have access to others. I think to start and move it I only need to reconnect the blue wires for the coil and drop the alternator belt and run it on the battery - does that sound right?

 

[AR67GTX]

Apparently the above connection was my culprit. I pried all the electric terminals out of the two plug ends - literally in the case of the alternator black wire terminals which were fused with the plug. One of the black terminals pulled off and it looks like they may not have trimmed enough insulation off when they crimped on the terminal and it was mostly crimped on insulation (thus pulling off easily). I put another terminal on it and connected all the wiring back up and wrapped them individually with electrical tape temporarily. I let the car run for about 15 - 20 minutes and the temp and gas level gages behaved normally. The alternator wire didn't seem to get hot and I don't see any sign of melted insulation anywhere that's visible - even right at the terminals so I may have dodged a worse mess.

My alternator gage is still climbing significantly and then jumping around wildly when I rev the engine up a little. If anybody has any ideas on this I would appreciate it. I had a meter hooked up and it never peaked over about 14.8 volts. Thinking about just replacing the alternator but that's just throwing parts at it.

I also need to come up with a 4-wire replacement plug set to repair the ruined/melted plug on the harness. If anyone has any spare or knows of a good source for that type thing I would appreciate hearing about it.

Edit: are type 56 series plugs and terminals common to Mopar? From the site I found, they seem to match the closest to what in on my harness. Automotive Retainers, Clips and Fasteners - ClipsAndFasteners.com

Thanks

 

[65-440]

Apparently the above connection was my culprit. I pried all the electric terminals out of the two plug ends - literally in the case of the alternator black wire terminals which were fused with the plug. One of the black terminals pulled off and it looks like they may not have trimmed enough insulation off when they crimped on the terminal and it was mostly crimped on insulation (thus pulling off easily). I put another terminal on it and connected all the wiring back up and wrapped them individually with electrical tape temporarily. I let the car run for about 15 - 20 minutes and the temp and gas level gages behaved normally. The alternator wire didn't seem to get hot and I don't see any sign of melted insulation anywhere that's visible - even right at the terminals so I may have dodged a worse mess.

My alternator gage is still climbing significantly and then jumping around wildly when I rev the engine up a little. If anybody has any ideas on this I would appreciate it. I had a meter hooked up and it never peaked over about 14.8 volts. Thinking about just replacing the alternator but that's just throwing parts at it.

I also need to come up with a 4-wire replacement plug set to repair the ruined/melted plug on the harness. If anyone has any spare or knows of a good source for that type thing I would appreciate hearing about it.

Edit: are type 56 series plugs and terminals common to Mopar? From the site I found, they seem to match the closest to what in on my harness. Automotive Retainers, Clips and Fasteners - ClipsAndFasteners.com

Thanks

Awesome, glad to hear you got it sorted out!

 

[AR67GTX]

Looks like I have a bit more work to do. I pulled the bulkhead connectors and found the big wire to the starter relay had got hot and melted the connector and bulkhead plastic around it. Again, except for the terminal being a little gunked up with melted plastic, I don’t see any melted wire insulation. I guess I need to push the bulkhead inside and examine the wires coming into it from the cabin side. I’m suspecting this may be causing the jumping amp gage.

Correction, when I pushed the bulkhead through to the inside where I could get a close look at it, I found two melted plug bays in the bulkhead and a spliced in piece of wire on the amp meter lead. Time for a new dash harness.