Help with electrical issue. Truck won’t start
 

I have a 91 N. intercooled W250. The cigarette lighter hasn’t worked since I’ve gotten it. Today I decided to replace the fuse and receptical. Along with the break and reverse lights and an electronic flasher. I drove it and picked up some supplies and came home and did all my changes. As soon as i turned the key to auxiliary the new cigarett lighter fuse blew and now the ignition won’t work. All other electrical things work normally (lights, radio, information center, etc) but I get nothing when I try to start it up. Any help would be appreciated.

I would disconnect whatever new work I did to the truck, and check all fuses with a test light, both sides, s÷ing if anything blew. Once I knew all fuses were good, I would look at the starter relay, and use my test light again to see if it's energizing the starter solenoid or not. Most likely you created a dead short, and burned up a fuseable link. A wiring diagram, or back tracing from the starter relay should put you in the ballpark for the correct fuseable link. You should buy, or borrow a service manual for this truck. I'm sure it's also available online ( the wiring diagram.

I'll bet the heater don't work. Everything you mention goes through the ignition-run circuit. In common is a fusible link, the ignition switch, and some connectors.

Ok. I’m still having this issue. I’ve checked the fusible links communing out of the duck foot and they are all good. All the fuses are good except I am not getting power to the first fuse labeled I/PNL LPS. Can someone tell me what to check next?

You would be helped by getting the FSM from Geno's for your truck. It has very good electrical diagrams.

You have a short in the circuit that supplies the cigar lighter which blew the fuse. When you replaced the fuse you probably took out the ignition switch or smoked the wiring. According to the 92 FSM the cigar lighter fuse is a 15 amp. If you used a bigger fuse than 15 amp you might have caused other damage. I have seen cigar lighters get messed up and short out. You could disconnect it and check the plug with the lighter out to see if it's shorted.

For the 91 it’s a 25 amp fuse for the lighter. I got that issue fixed. It was a short in the ground and now working. I put in a new ignition switch and still didn’t fix the issue of not starting. Thanks for all of your help. I’m going to keep at it.

Hopefully Somebody else on the forum will have an electrical diagram for the 91 and post some sections. I only have the 89 and 92 which are apparently different than your truck. There is a huge bulkhead connector at the firewall that everything feeds through.

Does the engine crank? if so you can run a wire from the battery + to the FSS (Fuel Shutoff Solenoid) on the back of the VE to enable fuel and get the truck to run. If it won't crank there is a relay on the left inside fender near the fusible links that controls the starter, assuming they use the same starting system as the 89.

I just guessing though. You really need the electrical diagrams to troubleshoot it.

Edwin

So I switched out the starter relay and everything and still couldn’t figure it out. I ended up taking to a shop who get it working. My question now is this. The shop informed me that the truck used to be an automatic that was converted to a manual. It was an issue with the old neutral safety switch from the automatic that was still on there. This is my 2nd first gen Cummins. ( Had a ‘92 two wheel drive 5 speed) and I cant see any difference between the transmission of my 92 and this one that was converted.

The Neutral safety switch is located on the side of the transmission on my 518 slushbox. You need to look for yours on your ride, which I would assume is on your clutch pedal.

Found this online.

A good example of chasing the wrong rabbit down the wrong hole.

Glad they were able to figure it out.