cootz

'93 Manual 4x4.

The other night I had the truck die on me due to a blown fuse which also feeds power to my PCM(not on the fuse block, but an inline fuse). I need some help identifying possible shorts.

In the picture of the main wire harness connection, does anyone know what cavity the jumper wire is attached to, what does it all feed?


This is the line that had the fuse blow upstream. Taking the PCM connector off shows that this line gives main power to the PCM (cavity #3).

The second picture shows the subject line. You can see there is a fusible link attached (22 gauge) and further upstream of this picture is an inline fuse that goes directly to my positive terminal on the battery. This is the inline fuse that blew.




It looks as though this in-line fuse was added by the PO. Should this fuse be here? If so, what amperage should it be.

With this fuse blown, I loose power to my PCM, which in turn shuts down my truck.

I jumpered the wire to the main harness to see what it fed to my fuse block. After jumpering, I had power to fuse terminals #1,2,3 & 7, 8, 9 (there may be more, but this is all I found).

Is this line suppose to be spliced into my main feed to the PCM?

As a side note, when the fuse blew, I must have had a voltage surge and my high beam on my headlights (both) blew.

A FSM wiring diagram would be useful if anyone has.


Any help is appreciative.

lowwag64

Hey Cootz,I won't be able to help you on this matter,but I just wanted to say that your wiring looks just like mine.alot of splices from previous owner and to small of gauge wiring from factory...

wannadiesel

That wire feeds the ignition switch, specifically the dark blue wires in the engine compartment that provide key-on power to everything. It also feeds the reverse lights and all the idiot lights in the message center, and the cruise. Doesn't narrow it down much, does it?

There should be fusible links in the area you showed, they probably blew before. If you are going to put a fuse in there it should be at least 30 amps.

cootz

Yeah I don't know if I'll ever find out what caused the short. I thought someone may have experience a similar situation especially with the headlights blowing.

I put a 30A fuse back in and everything is aok so far, just don't know when it will happen next is all. The trailer brake wiring looks like it was installed by a 5 year old. I'll probably start there, re-do and cross my fingers.

The last time this fuse blew was about 1.5 years ago when I hooked up to a buddy's trailer. As soon as I touched the brakes with the trailer plugged in, bam the fuse blew. After I unhooked the trailer, no more probs. I layed blaim on his trailer having a short somewhere (he also indicated others who had borrowed the trailer had issues). Not sure if this incident is related somehow, but I wasn't towing a trailer this time.

After reading some posts, is it necessary to attach a ground to the firewall and back to the engine on a '93? I know some were doing this on the early first gens due to the voltage reg...does this apply too?

farmer0_1

buy a reset breaker in place of a fuze at least it won't leave you high and dry most times.