Instrument Voltage Regulator / Cluster

-
SlantedMark4

SlantedMark4

'74 Valiant 225 /6
FABO Gold Member
Joined
Nov 3, 2022
Messages
110
Reaction score
54
Location
Switzerland
Hey guys
2 weeks ago, my '74 A Body almost catched fire from a burnt cable or so under the dash. It started smoking but stopped after I've pulled over and turned off the engine. The battery was barbecued so I think the voltage regulator went.
Now my actual question. I think the smoke that came from under the dash is a burnt instrument cluster voltage regulator. I've tried to see something from underneath the dash but haven't seen anything. Now, do i have to remove the whole cluster? And if so, how can I drop the steering column? Do I need to unscrew the cover on the column and then the two bigger screws?
 
Sounds right but check the FSM to make sure. Inspect the whole cluster and wires to make sure you see what it is.
 
Check the ammeter and it's connections. Make sure the battery is disconnected before you go digging under there.
 
When I was young and skinny, I could, "with difficulty" get an IVR out by reaching up under. BUT I WOULD NOT DO so in this case, because, "smoke." You may have fried something on the board or worse. I'd pull the cluster.

Disconnect battery!!!!

Remove the bolts for the column clamp at the lower dash, after removing trim piece. Remove or loosen bolts at the lower column floor plate.

Remove (unclip) speedo cable, pull cluster out some, reach around and unplug harness, and tip down and out until you can access the two (big red, big black) ammeter wires.
 
The instrument voltage regulator causing a dash fire is very unlikely. The copper traces on the circuit boards serve as fusible links, burn to open.
Smoke from under the dash usually comes from the big wires on the amp gauge. At some model (around 74) they went to a remote shunt design so the same small gauge wires for everything else were used to power the amp gauge. They even went through the same harness connector rather than bolt directly on the gauge.
My memory fails. That change could have been 75 and 76 only. You will remove the entire cluster before you find the problem. Good luck
 
My bad above. The change didn't happen until 75 model. Your amp gauge is right above the headlight switch. Water gets into this area which isn't good for electronics.
 
halifaxhops said:
Sounds right but check the FSM to make sure. Inspect the whole cluster and wires to make sure you see what it is.
Click to expand...
Thank you for your answer. I don't quite understand what FSM is cuz I'm new to this stuff and very new to electrical stuff.
 
CFD244 said:
Check the ammeter and it's connections. Make sure the battery is disconnected before you go digging under there.
Click to expand...
Well the battery itself is dead anyways. But I'll for sure disconnect it before doing stuff with those wires.
 
67Dart273 said:
When I was young and skinny, I could, "with difficulty" get an IVR out by reaching up under. BUT I WOULD NOT DO so in this case, because, "smoke." You may have fried something on the board or worse. I'd pull the cluster.

Disconnect battery!!!!

Remove the bolts for the column clamp at the lower dash, after removing trim piece. Remove or loosen bolts at the lower column floor plate.

Remove (unclip) speedo cable, pull cluster out some, reach around and unplug harness, and tip down and out until you can access the two (big red, big black) ammeter wires.
Click to expand...
You mean pull the cluster to see what actually burnt? TY sir for your answer!
 
RedFish said:
The instrument voltage regulator causing a dash fire is very unlikely. The copper traces on the circuit boards serve as fusible links, burn to open.
Smoke from under the dash usually comes from the big wires on the amp gauge. At some model (around 74) they went to a remote shunt design so the same small gauge wires for everything else were used to power the amp gauge. They even went through the same harness connector rather than bolt directly on the gauge.
My memory fails. That change could have been 75 and 76 only. You will remove the entire cluster before you find the problem. Good luck
Click to expand...
Thank you for your answer. I'll have to replace some cables anyways I guess. I have an old dashboard with all the cables and harnesses in my basement but new is better than original parts, right?
 
There IS NO free service manual for 74. The 73 is quite different, so far as wiring. I have a digital copy, but doubt you want to mail a USB quick clear around the world?
 
67Dart273 said:
When I was young and skinny, I could, "with difficulty" get an IVR out by reaching up under. BUT I WOULD NOT DO so in this case, because, "smoke." You may have fried something on the board or worse. I'd pull the cluster.

Disconnect battery!!!!

Remove the bolts for the column clamp at the lower dash, after removing trim piece. Remove or loosen bolts at the lower column floor plate.

Remove (unclip) speedo cable, pull cluster out some, reach around and unplug harness, and tip down and out until you can access the two (big red, big black) ammeter wires.
Click to expand...
Thanks for your help mate. I've done everything you told but I still can't pull out the cluster. It feels like it's still held back on the right side. Speedo cable is unplugged. I've tried from many angles but it never moved more than an inch.
 
No ideas. Make certain you didn't forget a screw, but doubt that. Might be part of the harness snagging the upper edge. You should, after lowering the column, be able to fold the cluster out and down sort of like opening a glove box, then lifting it up and out as the speedo kinda "hooks" over the lower edge
 
You must log in or register to reply here.
-

Back
Top