gkainz
Final Approach
KBJC-KCUT Thursday 1600 MST - Nice looking afternoon - 50nm vis, sky clear, winds relatively light ...
Stopped at Lusk, WY for fuel, started back up in the dark, noticed the lights seemed a little dimmer than usual, but not significantly. Headed north again, with a lot of lightning, towering cumulonimbus NW that seem stationary and are reported to be still north of KCUT.
5 minutes north of KLSK, the GEN warning light comes on and voltage shows low. No mechanics available at Lusk this time of night, so I shut down all unnecessary electrical draws inside; GPS, radio, dim the panel lights and press on north. Another 5 minutes north and RPMs come up and speed drops about 20%. I limp on in to Custer, with a few raindrops spattering the windscreen but the lightning show remains NW.
The next day I determine the alternator is not producing, so I swap it out. Hmmm, the new one isn't producing, either! Find out that the Voltage Regulator function is performed by the Primary Control Module, and an external voltage regulator can be added externally. Rig up a small wiring harness, add an external voltage regulator and waddaya know - charging!
KBJC has winds at 20G40 throughout the weekend, with significant turbulence reported, and I have turkeys to chase and trout to catch, so I pursue those activities with some success until Sunday midday.
Head back to KBJC and I still have the higher than normal RPMs with a 20% reduction in cruise speeds but at least I have an electrical system! So, a slower trip, but I trade the extra time with GPS and radio play.
Today in discussing the issue with my mechanic, it appears that the PCM (the computer) went out and will need to be replaced.
Anyone have a good lead on a PCM for a '97 Dodge Cummins 2500 4x4? Seems they decided to allow the computer to control voltage regulation as well as transmission overdrive functionality. So, while I was able to bypass the voltage regulation with an external setup, there appears to be no easy way to get the transmission out of limp mode and turn overdrive back on. (hence the RPM increase and cruise speed reduction)
And you were ready to flame me for continuing into IMC and thunderstorms with a failed electrical system?
Stopped at Lusk, WY for fuel, started back up in the dark, noticed the lights seemed a little dimmer than usual, but not significantly. Headed north again, with a lot of lightning, towering cumulonimbus NW that seem stationary and are reported to be still north of KCUT.
5 minutes north of KLSK, the GEN warning light comes on and voltage shows low. No mechanics available at Lusk this time of night, so I shut down all unnecessary electrical draws inside; GPS, radio, dim the panel lights and press on north. Another 5 minutes north and RPMs come up and speed drops about 20%. I limp on in to Custer, with a few raindrops spattering the windscreen but the lightning show remains NW.
The next day I determine the alternator is not producing, so I swap it out. Hmmm, the new one isn't producing, either! Find out that the Voltage Regulator function is performed by the Primary Control Module, and an external voltage regulator can be added externally. Rig up a small wiring harness, add an external voltage regulator and waddaya know - charging!
KBJC has winds at 20G40 throughout the weekend, with significant turbulence reported, and I have turkeys to chase and trout to catch, so I pursue those activities with some success until Sunday midday.
Head back to KBJC and I still have the higher than normal RPMs with a 20% reduction in cruise speeds but at least I have an electrical system! So, a slower trip, but I trade the extra time with GPS and radio play.
Today in discussing the issue with my mechanic, it appears that the PCM (the computer) went out and will need to be replaced.
Anyone have a good lead on a PCM for a '97 Dodge Cummins 2500 4x4?
Seems they decided to allow the computer to control voltage regulation as well as transmission overdrive functionality. So, while I was able to bypass the voltage regulation with an external setup, there appears to be no easy way to get the transmission out of limp mode and turn overdrive back on. (hence the RPM increase and cruise speed reduction)And you were ready to flame me for continuing into IMC and thunderstorms with a failed electrical system?
Last edited:
