Alternator and PCM differences between 91.5 and 92

[Niki]

So, I was looking over the fleet the other day and happened to notice a voltage regulator on the firewall of my 91. 5. Looking further, I see it has no crank sensor. Its been a while since I had a pre 92 truck. My 92 and 93 both have no regulator, but a crank sensor. Everything has a PCM. The alternators appear the same also. What is the PCM on the 91. 5 for, just the grid heaters? Are the alternators really the same? If I use my extra 92 motor for a repower can I just hook a regulator up to that alternator? Thanks.

 

[Ncostello]

I have a 91. 5 and have never noticed a regulator on the firewall. My alternator has quite the deal on the harness. One wire with a 10mm nut for the positive... and some large deal on the wires that bolts to the back of the alternator pins using small 7mm nylock nuts and a 10mm nut to hold all the wires against the alternator.

 

[PToombs]

NC, the one that holds the wires, is the ground also!



Niki, I'm pretty sure the alternators are the same. They just use the PCM instead of the regulator.

 

[Moab4x4]

And yes, you can use a regulator or the PCM to regulate the alternator. I have done both with the same alternator at different times for different reasons. I think on a repower I would drop the PCM. I like mine cause it gives me cruise control. Everything else could be done with discrete components a bunch cheaper. I would use a Mopar voltage regulator and a push button switch for the grid relays as I don't need them that much anyway. I have run an OD solenoid on a switch, but now I just use a Getrag.

 

[bgilbert]

I have run an OD solenoid on a switch, but now I just use a Getrag.

:-laf:-laf:-laf I like that one!

 

[Kirwin]

91.5 differences

When the intercooled engines came out they added the PCM for transmission control of the shift to OD and also added computer controled cruise control. The PCM replaced the little black box that controled the grid heaters (WTS light) and the WIF light that was used on the 89-91. 5 non-intercolled trucks. My 85 Ramcharger conversion has the early PCM and thus has the seperate MOPAR voltage regulator. Alternator is the same. You could always add the clip on style voltage regulator that mounts on the back of the alternator. Ken Irwin