Author Topic: Gauges Die Under Electrical Load  (Read 842 times)

Offline rojpon74

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Gauges Die Under Electrical Load
« on: December 30, 2021 - 01:22:46 AM »
Hi Everyone,

Been stumped for a while with a recent gauge issue on my '72 Challenger 318/A-904-LA I've been trying to solve and am looking for some help on possible causes. 

Basically, the fuel, temperature, and oil pressure gauges on my Rallye dash all die out/lose power when the engine is at idle, e.g. at the stoplight, and the electrical system is under heavy load, e.g. headlights, heater, rear defogger, brakes lamps all on at the same time.  The gauges all come back to life once I accelerate and the RPMs increase.  Gauges die out again when I come to a stop and the cycle continues.  Nothing else seems to be affected by this issue.  I checked the battery at the battery terminals with the engine off and it's a little over 12 volts.  With the engine running at idle, voltage at the battery terminals is around 13.4-13.5 volts.  I also just replaced the voltage regulator at the firewall to no avail.  I'm thinking the cause could either be the alternator since the voltage at idle is under 14 volts (alternator is a Mopar re-manufactured, 60 AMP unit, circa 1995).  Or is it possible the instrument panel voltage limiter, a solid state instrument panel voltage limiter from Real Time Engineering, could be the culprit?

Thoughts? Ideas?
R. Soriano
- 1972 Dodge Challenger
- 2007 Dodge Grand Caravan SXT
- 2012 Dodge Journey R/T




Offline 70chall440

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Re: Gauges Die Under Electrical Load
« Reply #1 on: December 30, 2021 - 11:20:37 AM »
This has nothing to do with the alternator or your VR, it has to do with the instrument cluster and its connections and/or wiring, but yes I would suspect the voltage limiter is the culprit.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline rojpon74

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Re: Gauges Die Under Electrical Load
« Reply #2 on: December 30, 2021 - 12:22:50 PM »
Thank you!  8)

This has nothing to do with the alternator or your VR, it has to do with the instrument cluster and its connections and/or wiring, but yes I would suspect the voltage limiter is the culprit.
R. Soriano
- 1972 Dodge Challenger
- 2007 Dodge Grand Caravan SXT
- 2012 Dodge Journey R/T

Offline 70chall440

  • Sr. Resident
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Re: Gauges Die Under Electrical Load
« Reply #3 on: January 01, 2022 - 07:47:05 PM »
Welcome
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)