Just joined this forum today. Spent many hours looking at it last night. Great! My 93 has been giving me fits. Charging problems. Volt meter takes a dive, lights dim etc. Worse when I pull the 5th wheel RV. Rig is in nice shape with only 126K. Replaced the pre-heater sensor and when that didn't work I disabled the heater by unplugging the relays. No effect on the problem. Took it to a dealer in Vegas on my way home last fall and they diagnosed the computer/VR as the culprit (apparantly an integrated unit) and replaced it. Didn't solve the problem. Got home to Idaho and replaced the Alternator. No dice. Problem is getting worse and I'm afraid to drive it far from home now. While looking at the posts last night I discovered the thing about no ground from engine to firewall and alternator to VR. Will try that tomorrow and see if it helps. Hope I can solve this problem as the pickup is nice and was very affordable. Once I do I'll look into a little more power and some transmission mods. I pull a 29ft low profile areodynamic lightweight RV (Shadowcruiser) but don't get great mileage like I did with another 93 4WD with a Getrag.

 

Adding a ground is allway a good idea allthought it probly was more related to the earlyer 89-91 that had a VR on the fire wall!

remove the battery terminals and clean them even thought thay may not look line thay need it!

the hot wire from the bat to the alt needs to be compleatly clean.....no corrosion anywhere!

You now the ground issue could still be worth a try......temperary jumper cables would prove it!

allso you need to look at the conecter for the computer,black box VR....what ever you want to call it!
if the conectors have any corrosion it could cause you problem

 

First thing check the reg ground, make sure the battery cables are clean and connected well on both ends. As for the volt gauge they arent greatest in the world.

If you have an analog volt meter check volts on battery without it running, then crank it and recheck, it needs 14.5 , it should maintain that even with a load.

 

Check the crank sensor an the wires that go to it. The computer needs to get a signal from the crank sensor or the alternator field will not be energized.

 

Also check the alternator wiring harness under the hood from the alternator to all first connections under the hood. Look for something green and possibly furry looking and you might have found your problem. Also take a look at the bulkhead connector where the harness goes thru the firewall. Clean and grease with an electrical contact grease.

 

What wannadiesel said. Pay particular attention to where the wires go thru the clip at the front of the head. The connector hangs below this, and the weight tends to abrade the insulation off of the wires. Intermitant grounding can and does result. Then the computer doesn't know the engine is running, and doesn't energize the alternator. Along with other things!

 

Thanks Wannabe and all you guys for the input. I went through all the grounds and cleaned everything up even though it all looked good. Teeny bit of corrosion on the pin connector to the computer/VR. No effect on the problem. The only voltage I get out of anything now is battery voltage which is going south until I can put it on a charger. The crank sensor thing is interesting. There has been some disagreement among folks I've asked (parts counter people) as to whether it even has one. Will look into that and the wiring harness next. Will also take the alternator in for a bench test. It and the computer are only ten months old but you never know. This problem is beginning to tax my normaly sunny disposition! This pickup is really clean, you open the hood and it looks nearly new. Looks better under the hood than it does on the outside. Didn't suprise me when my ground cleaning project didn't get results. Gremlins! You guys are great, thanks for the help, will check back in a couple days.

 

if it's 91.5 or newer it has a crank sensor, and it have the VR in the black box on the fender!

 

You might want to peel back a bit of insulation from battery cables near the lugs that connect to battery posts. If you see any green corrosion on the wires toss them both and buy new, they're cheap. This is a very common cause of electrical problems on an older vehicle.

 

You could also check voltage directly from the alternator to determine if the problem lies in the wiring somewhere. The fusible link block on the driver's fenderwell is a known trouble spot for wiring issues. I had to make some repairs there on mine for an unrelated issue.

 

When I was having electrical issuses I unbolted the ground wire, among other things, from the engine block and found it full of water and rust. I cleaned it and lubed it and so far I have had no other electrical issuses.