Bill, I’ll check the power at the IVE and let you know. Do you know if the headlights are tied into the instrument circuit? It does not make sense that they would be but the electric diagram I have is difficult to read so I may be missing something. Another item that I recently realized, is that I do not have an engine ground strap. I did not remember removing one when I took the car apart 3 years ago. Could this be causing problems? I’ve read where the 1970 does not use one, but then I read other posts where people say it does.
Midlife, thank you for the information. I’m going o pull the gauge cluster tonight and I will check the alignment and the resistance at this time. I’ll report back. Thank you
Power to the IVR (Instrument Voltage Regulator) comes thru the instrument panel printed circuit connector pin 12 from a violet resistance wire fed by the ignition switch. No connection to headlights. You are correct that the 70 did not use engine (or alternator) ground straps.
Glad to learn about the potential short - something to watch for when reassembling dash.
As to a engine ground strap, you need one if the factory style ground wire is not used. It has a lug that gets mounted to one of the Voltage Regulator mounting fasteners giving a body ground, then goes to the engine block for the engine ground.
I’ve gained access to the IVR. Which side is current in and which side is current out? Here is a picture of what I am seeing. I’m assuming i check it in the car while still attached to the cluster, correct?
The voltage into the cluster at pin #12 has 12v. So the power into the cluster is good. Can i check the IVR on a bench now that the cluster is back out of the car?
I’ve done the resistance checks and they all checked good. I’ve checked the grounds in the harnes and they also appear to be good. I have power going into the cluster at pin #12. I’m thinking that the IVR must be the problem but the electrons shop that rebuilt the cluster is reputable and they told me the IVR was replaced. However i still can’t rule it out.
I know you’ve got it running now but wanted to share a no spark experience I had with my old 2v 351C in a 69 Mustang. In my case the roll pin that held the distributor gear in place had sheared off while doing a burnout. She just died suddenly and was lucky to figure it out pretty fast when I had someone crank it over while I looked for spark at the points and realized the rotor wasn’t turning. Just an FYI for future diagnosis of no spark problems.
The sheared roll pin on the distributor drive can be even harder to diagnose when the gear hangs on the broken pin at times and the engine runs, then other times it still turns the distributor but the timing is way off and the engine backfires either through the carburetor or the exhaust. That had me going for a long time when it happened on my '70 with a 351C a few years ago.
If I remember correctly most of the pieces were still in the gear and shaft, I was around 17 yrs old when this happened. Many moons ago. I was lucky the gear stayed on the distributor shaft when I pulled it also.
