Voltage issue (92 12 valve)
#11
12-28-2021, 03:40 AM
i don't think the crank position sensor should effect overdrive but it will effect the charging system if bad. it will not ground the asd if it doesn't sense that the engine is running. stupidly enough on the diesels all the asd relay does is power the alternator 12v field wire.
who said you have to always have to test for power at the battery? last time i checked there is many places in the cab that you can hook up a multi meter to check voltage while driving.
who said you have to always have to test for power at the battery? last time i checked there is many places in the cab that you can hook up a multi meter to check voltage while driving.
#12
12-28-2021, 06:44 AM
#13
12-28-2021, 11:08 AM
I know I'm not supposed to tow with overdrive on
Last edited by BM9NBA2; 12-28-2021 at 11:12 AM.
#14
12-28-2021, 12:43 PM
The major things to check with a voltage issue on these with a PCM controlled alternator is the cross over cable, battery connections in general for corrosion, tightness, cracks, ect. Next is a good clean connection for the alternator cable, next make sure all chassis, engine and body grounds are clean and solid. Wouldn't hurt to test the battery with truck running for A/C voltage indicating a failed diode trio. A/C voltage in a DC electrical/computer system does some wacky stuff
Im not sure if these 1st gen bodys are the same as newer ones in that they read voltage off drivers side and charge passenger side? I believe the PCM is located behind the drivers headlight in the fender but I might be incorrect on that, assuming im correct that would mean it reads on charges the other. Wouldn't hurt to run a jumper cable between battery posts to see if the issue is resolved that way indicating a poor crossover cable. Personally I had my alternator wire extended to charge the drivers battery, after boiling a new battery, I decided that wasn't going to happen again
Im not sure if these 1st gen bodys are the same as newer ones in that they read voltage off drivers side and charge passenger side? I believe the PCM is located behind the drivers headlight in the fender but I might be incorrect on that, assuming im correct that would mean it reads on charges the other. Wouldn't hurt to run a jumper cable between battery posts to see if the issue is resolved that way indicating a poor crossover cable. Personally I had my alternator wire extended to charge the drivers battery, after boiling a new battery, I decided that wasn't going to happen again
#16
12-28-2021, 07:10 PM
Voltage is surging quite a bit,
When I was driving today though it was going all wacko.
When I was driving today though it was going all wacko.
#17
12-28-2021, 07:42 PM
It goes down to what the voltage is when the truck isn't running with just the key on. I think it may be the grid heater that's causing the issue because that's about where it goes to. The grid heater functions properly when warming up though I always let it go through its cycle. These trucks didn't have lockup till 95 except for the gas trucks they had it since the 80s I believe.
#18
12-28-2021, 08:23 PM
It doesn't go over its normal voltage of 14.4-14.7. I'm gonna unhook the grid heater tommorow as I've already cleaned all the connections so one of the relays must be acting up or something.
#19
12-29-2021, 03:49 AM
All Star
Im not as familiar with these as Id like to be, newer trucks cycle the grid heater based off intake temp/road speed after the the truck is running. Are these using some type of sensor/timer to cycle the heater? Could that temp sensor be faulty, RE trans I know for sure will change shifting based on cold temps. Would the RH/727 remove OD if said temp is also to low. I know alot of speculation/guessing just ideas to think about. I know even my old 5.7 would cycle the plugs after running but I never had to deal with the voodoo module that does it
#20
12-29-2021, 11:03 AM
Im not as familiar with these as Id like to be, newer trucks cycle the grid heater based off intake temp/road speed after the the truck is running. Are these using some type of sensor/timer to cycle the heater? Could that temp sensor be faulty, RE trans I know for sure will change shifting based on cold temps. Would the RH/727 remove OD if said temp is also to low. I know alot of speculation/guessing just ideas to think about. I know even my old 5.7 would cycle the plugs after running but I never had to deal with the voodoo module that does it