Instrument panel voltage regulator questions

Hi, I recently had my ignition switch go out, so while the car ('67 200 conv. AT) was parked I decided to replace the IVR as mine was acting weird. Well I had a brand new one laying around that I had ordered from CJ Pony Parts. The installation was easy and straightforward, I don't see how you could mess it up because the wires and prongs are designed to mate only one way. Upon installation, the gauges were a little sluggish at first but then everything worked properly for a couple of days. Then today the gauges all read nothing, then later as the car and the weather got warmer the gauges looked ok, then later the gauges all pegged at max! Fuel, Temp, and Oil pressure are affected, the speedometer is fine, and the ameter never worked since I got the car 17 years ago. Also, the instrument lights dim in rhythm to the engine turning at times. Anybody have a suggestion? Could the problem be anything other than a defective Inst. panel voltage regulator? As always, any insight most greatly appreciated.  

mytbison:
Hi, I recently had my ignition switch go out, so while the car ('67 200 conv. AT) was parked I decided to replace the IVR as mine was acting weird. Well I had a brand new one laying around that I had ordered from CJ Pony Parts. The installation was easy and straightforward, I don't see how you could mess it up because the wires and prongs are designed to mate only one way. Upon installation, the gauges were a little sluggish at first but then everything worked properly for a couple of days. Then today the gauges all read nothing, then later as the car and the weather got warmer the gauges looked ok, then later the gauges all pegged at max! Fuel, Temp, and Oil pressure are affected, the speedometer is fine, and the ameter never worked since I got the car 17 years ago. Also, the instrument lights dim in rhythm to the engine turning at times. Anybody have a suggestion? Could the problem be anything other than a defective Inst. panel voltage regulator? As always, any insight most greatly appreciated.

The job on the IVR is to provide a constant voltage to the gauges that is stepped down to 5 volts from the cars random 12-14 volts. Gauges need a constant/precise level of voltage to operate correctly since they must operate in very precise manner compared to the rest of the car's electrical system.  The symptoms you've quoted all follow a defective IVR (even though its new).

However, one cause of your dimming lights is you may still have an issue with the mechanical charging system voltage regulator. The mech VR is susceptable to engine speeds and temperatures ranges that the electronic versions are not.

There are electronic IVR's available with PEIVR technology that eliminates the issues with standard IVRs. One I'm familar with is made by Coast, has pretty good specs and they're around 30 bucks.jlg  

jlg, thanks very much for the information. So, if you were I, you'd replace the charging system voltage regulator with a new one, and replace the defective IVR with an electronic one, correct? Thanks again for your help, I really appreciate it. I have installed a defective fuel pump, ignition switch, thermostat, spark plug wire, and IVR all in the last year. Parts aren't what they used to be!!  

When I rewired my 65 coupe my gagues all did that too for a bit. I had to double check the wires going to the gagues themselves. I ended up switching them around untill it worked. but the pulsating lights might be a battery thing, the battery might be getting low and it could be that and in combination with a failing alternator, but I wouldnt read too much into that part of it. And did u get it from the CJ Pony parts in York PA?  

CJ's is in Harrisburg, PA, about 25 miles from York. I have been a customer of their's for many years. Although the availability and variety of parts has exponentially increased since the early 90's, I can't say the quality of the parts has. Win some/lose some. It's got to be a lot to manage. The gauges used to work fine, then started getting a bit wacky about a year ago. But nothing like this. Didn't change any wires going to the gauges. I feel the pulsating thing is unrelated, but I mentioned it because I want to give the people on this board all the information I can. It's such a great source of knowledge, people are generous with their expertise, I feel lucky to be able to tap that when I don't know for sure. Thanks!  

Another thing that can cause flickering lights is the light switch (thanks MM for the blog on the site that discusses this issue deeper).
Personally, I would have the electrical system checked for voltage fluctation and if it's OK, go after a new head light switch first.jlg  

Thanks, the blog was an informative read. Can't help but learn useful stuff around here.  

Hey, I'm back with an update and related questions. I replaced the charging system voltage regulator with a new electronic one, replaced the headlight switch, and replaced the IVR again, this time with an electronic one as suggested. I do not see anything odd in the wiring. My oil pressure and temp gauges now read consistently but very low so I will adjust them. The fuel gauge, however, is still wacky. It has a new sending unit. If I fill the tank, the gauge reads a little more than half. Invariably, the next day the gauge reads empty. Do you think it needs that much adjustment? What does this sound like to you? Thanks in advance for your help.  

mytbison, I've been watching the thread and have a 66 coup. It has, so far, had none of the things happening. But at the risk of being a traiter on a Ford forum, I have had the same exact thing happen on my 78 Pontiac Trans Am.

A new headlight switch brightened up the whole gauge cluster and stopped the occasional dimming of everything. Don't know why - although a ground wire was worn through on my voltgage gauge and was randomly shorting on a metal dash support.

And the original oil pressure gauge continues to flick around. I bought an aftermarket 3 gauge set and hooked it all up. I wired a Y to the old and new oil pressure gauge just to check, and sure 'nuff the new one didn't wiggle. It was the old gauge. Good luck, I know stuff like that can drive you crazy!  
Brazil

Also on that sending unit, I would hardly think it would need any adjustment if it's a new one made for the car. Do you think there's a chance it's binding on the tank inlet some way? I can't see it showing empty - when it does this does it affect driving in any way?  
Brazil

Thanks for your reply. The PEIVR electronic IVR came with instructions for making slight adjustments to the gauges, but not as wholesale as what is needed here. Car drives great these days, regardless of what the gauges say. I will double check the fuel sending unit again, but I looked at it before and it looked normal. When I replaced the charging system voltage regulator and the headlight switch, the instrument light pulsating stopped. The initial replacement of the IVR with a new mechanical one yielded fine results for a few days, then the gauges went wild. I did put this new PEIVR in before I changed the VR, wonder if something got damaged by the old VR.