Originally Posted by tensley
Hey guys. On my 1991 JGW I finally got my power seats, rear defroster, and rear key switch fixed. It was a fusible link, however here is my new problem. While running in park the voltage gauge reads around 14.5-14.7. As soon as I put it in drive (not moving) the needle drops down to around the low 13 or below 13. Put it back in park it jumps right back up. While I'm driving it is around high 13 to low 14 but as soon as I come to a stop sign or red light it drops right back down. My battery is new and I had my alternator checked last night at O'reillys and it checked good. This all started last week after replacing the fusible links. I know they are good because all of the devices are still working with no problems. Is there anything that I still need to check or do? I'm at a loss. Thanks
Your alternator must replenish the amperage given up by the battery when starting, so it's regulator is putting out 14.5-14.7Vdc, this is normal, putting the vehicle in drive provides a load to the engine, and therefore its RPM level drops and therefore the alternator drops output simply due to the fact that the engine spinning the crankshaft pulley at a lower revolution and therefore the belt is spinning slower, and therefore the alternator pulley is spinning slower, and therefore the alternator's output is lower...by design.
Try standing on the brake in drive and press the accelerator to get the rpm's higher, the voltage should go higher.
Make sure you close the garage door and pull right up to it and do the above experiment...
Joe Guilbeau<br />1983 Cherokee Laredo WT (SJ-17), 360/229/727/D44/D60 4.10 Gearing, 8-lug hubs, Edelbrock Performer w/EGR Intake, Mallory Unilite Series 47 Photo-Optic Infrared Trigger Vacuum Distributor, Mallory Surge Protector, Mallory Promaster Coil, Holley Pro-Jection TBI 502-Analog, FlowKooler High Output Water Pump, Staggered 4-Core Custom Industrial Radiator, HD Fan Clutch, Dual Electric Fans, CS130 Delco 105-Amp Alternator, Oil Bypass Mods at Rear of Block and Distributor Oiling, Superlift 4\" Suspension, Rancho RS5000\'s, Hi-Tech 31\" Re-Treads, Aero 33 Gal Tank w/Skid Plate, Custom Rear \"Longhorn\" Bumper