I was commuting 60 miles north to take a class and I looked down at my gauges and noticed my temp starting to rise, luckily it stayed at the 3/4 mark on the temp gauge (replacing the thermostat tomorrow, think it might be stuck about half open, the needle usually sits about 1/2 in the gauge when properly warmed up...).

I hit a bump and next thing I know I have no oil/brake idiot lights, the temp gauge goes dead, the fuel gauge goes dead, but I still have cluster lights, turn signal lights and all the dash knobs work....a few minutes later for no reason the needles all wake up go to maximum then settle back down to their original positions....

Think I'm looking for a bad connection and changing the Voltage regulator just in case....


Weird....

-D.Idiot

LOL, D'OH!!

Sounds like either the regulator or a loose connection to me, too. Luckily I'm almost done with all my underdash wiring until I'm ready to make my custom plate and change out all the gauges

That cracks me up that it seems I'm getting a rep for electrical gremlins and making a nitwit of myself with my occasional dumb mistakes

_________________
'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

D.I., your voltage limiter behind the dash is going out. It knocks the voltage down from 12V to around 5V or so to run the guages. Its a little rectangular box, I think just off the ampmeter.

Where's that myth bout the instrument cluster voltage regulator changing 12 volts to 5 volts come from? Sheese.... it provides 12 volt pulses!! 12v-0v-12v-0v-12v-0v-12v-0v-12v-0v-12v-0v-12v-0v-12v-0v- all day long. Sometimes the contacts in it stick and temporarily makes the gauges read high. Eventually the heater in it burns out at which time it sends full 12 volts to the gauges all the time and burns them out!! Connect your low wattage 12 volt test light to the wire connected to your temp sensor, you will see it blink on and of if all is well.

Thanks man, I know where it is (it'll be fun with my 'meaty fists' getting in there).

I checked the Wiring diagrms last night and my two culprits for those specific items are the voltage regulator, and a 3 amp fuse in pod #5....


Will post my results, thanks!

-D.Idiot

p.s. the regulator is an echlin unit that I installed 14,000 miles and 18 months ago...sheeesh

If you changed it out that recently, I would think it'd be electronic. If for whatever reason it's not, here's a Mopar Muscle article that I went by to convert to electronic (and it works great):
http://jefframin.org/library/IVR.1.jpg
http://jefframin.org/library/IVR.2.jpg

_________________
'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG



Know how they always build a better idiot? That's me

Craig, if you look at a wireing diagram in the factory shop manual, you will see that the voltage limiter has 12V going in, and 5V going to the temp and fuel guage. In pulses.

Jopapa and Duster idiot you broke the cardinal rule which states: Its what you DIDN'T replace and thought about doing at the time. Agree check dash regulator and for any loose/questionable grounds. At least you didin't have a nagging ghost like in damp weather a tendency to stall and restart itself with no human needed, never was able to track this down. Complete and I mean complete rewiring solved this dangerous problem.

Well I pretty much replaced everything but the speedo and that one welded splice that the 10awg black wire connects to, so at least if something fails I know what to go after

_________________
'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG



Know how they always build a better idiot? That's me

My voltage regulator was bought 14,000 miles ago (18 months) and was a brand new Echlin unit...all the bulbs in the cluster are new, and I checked the circuit board when I rebuilt the car....The problem lends itself to being a 76 and a one year only wiring and cluster nightmare.

The voltage regulator grounds itself on the steering wheelfoot pedal support when the cluster is engaged, that is standard per the wiring diagram....

I pulled the cluster this morning, checked everything nothing out of order, i replaced the voltage regulator with a new one, put the unit back in and everything works fine except for the temp gauge...it's dead (I ran it down the highway with my foot in it to get it up to 'operational temp'....)

after re-checking everything, all my wiring connections are sound, but the cluster harness isn't staying seated, and the voltage regulator seem a bit loose in it's socket.... something tells me I'd better be looking for another 1976 cluster before this one fails out/breaks....


jeeez....

-D.Idiot

Jopapa that 10GA splice is what started all my problems, seperated and shorted out to ground with interseting smoke effects .

It came undone on its own, or you cut it? Suddenly I'm glad I rewrapped mine good and securely

_________________
'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG



Know how they always build a better idiot? That's me

D.I., if the regulator goes bad, it can fry the guages since they got to much voltage. Bummer dude! Why is the '76 cluster one year only, the change to the F bodys have anything to do with it?

Jopapa came undone by itself, judging by the dammage to the wire had been in failure mode for some time, still can't imagine what kind of resistence would cause this to un-weld and yet leave the gauges unaffected. Also found evidence of a band-aid repair complete with acorn nuts! Dave

Freakin' cluster... *grrr*....


'76 is the one off, they 'improved it' then cancelled the A-body for the F-body....

here are a couple of pics to tell the differences, you can swap circuit boards, and amm gauges to make a '76 cluster work in a 1973-1975 car, or vice versa....

Ammeter's are different due to the 'shunt' wired into the 1976 car....

The amm on the left is from a 1975 cluster, and is directly wired to the alternator...the amm on the right is the 1976 unit and is wired to the alt through the cluster circuit board and voltage regulator....



This pic shows my '76 cluster in the fore ground and a 1974 cluster in the background...note the different circuit routing, and the lack of 'condenser' on the 1976 models....




Another noted difference is the fact the 1972(?)-1975 clusters use a bigger light receiver than the 1976 units (no interchange possible except for the #158 lights). The one on the left is the 'old model' and the other is a 1976....






The two 'culprits' of my problems were these two %$#^$%'s here:

The cluster prongs, and the VR socket.




the cluster socket isn't staying tight to the prongs, and some of the prongs are getting 'wobbly'...next time I have this out, I'm going to solder the prongs , but that will only be temporary, I'll have to find a better way to R and R those things....
The voltage regulator was very 'loose' in the socket... causing those two gauges to go dead when going over 'rough' terrain....pulling the board, and pinching these a bit with pliers made the new VR stay in place with no wobble...





everything's back up and running fine, tomorrow I'm swapping out the thermostat to a cooler one, my dash turn signals are a bit finicky, but that's because of the cluster prongs for that circuit are a bit 'wobbly'...


anyone got another 1976 cluster they want to trade for a 1975 cluster?


that was too much fun for today....let's not do it again any time soon...


-D.Idiot