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Wiring issues

Clint Bazemore

Active Member
Nov 26, 2017
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Mebane, NC
Me again. Just picked up a 1986 D150 short bed. Thinking about selling my 4X4. Getting older and the Two wheel drive is closer to the ground. Having a voltage problem from under the hood to under the dash. Truck has starting issues. I have checked the wiring from the battery to the bulkhead connector. Getting battery voltage. Go under the dash at the bulkhead connector and get battery voltage. Turn the key on not running and the voltage drops to 4 volts and lower. turn the key off and the voltage goes back up. Unplugged the bulkhead connector under the hood and everything looks very clean. Looked under the dash on my 88 W150 and no change between key on or off. What can go wrong between the firewall sides? Not all fuse circuits are getting power either. Have been looking on Aldata with no good wiring diagrams to show all the wires from one end to the other. I built an ignition in a box and the engine runs great. Thanks again for any help in this area.
I have not checked that area yet. Just can't understand how power can change from one side of the bulkhead to the other on at least three different wires.
Have you load tested those wires. Check for voltage drop and replace the offending.
Other than turning the ignition switch on and off I have not. Watched a few videos on YouTube about replacing all the power circuits to get rid of the fuesable links. I think that might be a quick repair versus driving myself crazy just looking for the issue.
Did you check the voltage on the firewall side of the bulkhead with the ignition on? I know you checked there first, but check it with the circuit loaded and connected
Yes. Everything connected and under the hood I am getting battery voltage before and after the fuesable link key on or off. Under the dash I get battery voltage until I turn the key on not started. Voltage drops to 4 volts and less.
7mopar suggested checking the ammeter, check power on both sides of it with the ignition on and off
It will be Friday before I can get back to the truck. I will take more test equipment and check everything that has been brought up. Thank you all.
If the connectors at the amp meter are good, clean them, add dielectric grease and put them both under one of the nuts to bypass the amp meter. An amp meter is a dash fire waiting to happen.
Thanks for the input. My gauge is part of the cluster and a plug. I got a chance to go tinker with the truck this weekend. Found a fuesible link that was not playing right. Cut it out and ran a jumper wire to the wire. Full power at the fuse box. But I think I am missing a few relays beside the steering column. Gets hot and humid real quick around here lately. Maybe a couple hours Friday morning.
Me again. Went to work on the truck this morning. Same issue with the wiring. I have done more research and think my issue is the bulkhead connector itself loosing contact. Unplugged it and ran a jumper wire to the inside plug and power stayed the same after turning the key on. Before the voltage would drop a lot with key on not started. My question is about replacing the bulkhead connector. I will never pull the truck apart so I could just strait wire it with no problem. Any other ideas would be great to hear. As always thanks for the help.
Wiring it straight through works, I have seen people drill out the connector after removing he offending pin and push the wire through
I think that will be the path I take. Hoping for enough slack under the dash that I can do this all in the engine compartment. Too old to lay in the floorboard more than 10 to 15 min. I will pull out the connector and cut all the wires so I can take it to the garage at home. It has AC. I'm thinking butt connecters should work if crimped properly. Thanks for the input.