Electrical issues

[GGrossman]

Hey guys and gals,

I have a 91. 5 W250 with a electrical problem. I have no brake,tail,head,parking,or dash lights. The brake lights will come on if I use the button on my trailer brake box. Also the power door locks don't work. I came home from work and everything worked. I adjusted the rear brakes and checked voltage on the TPS because I think that might be going bad. I went to leave that night and I had no lights or power door locks. Could it be the head light switch? I checked the fuse box and all the fuses seem to be good. So I don't know what else it could be, any help or advise would be great

Thanks in advance

Grossey

 

[R C Cola]

Fuses ?

Simple things first. Fuses seem to be good ??? Use a test lite or a fuse tester

sometimes they look good but do not carry juice. Make absolutely certain that ALL fuses are good. RC

 

[DBF]

Power door locks come off fuse 6 - 20amp and don't go thru the headlight switch. Brake lights come off fuse 5 - 20amp and also don't go thru the headlight switch. The dash lights that change brightness with the brightness control on the dash come off fuse fuse 4 - 20amp before the headlight switch, then fuse 14 - 3amp after the brightness control on the switch. Horn comes off fuse 4 as well, but does not go thru the switch.



All the above things come off one fusible link in the bundle by the grid heater relays. It's a short length of 18guage grey wire that goes into a 12 gauge red/white wire. If that got opened up somehow, all those symptoms would exist.



If some of these other things aren't working, then it isn't that link:

Does the dome light come on?

Power windows work?

Does the engine start?



Tell us more. DBF

 

[GGrossman]

more info

Dome light comes on when door opens and when head light switch is rotated

power windows work

power mirrors work

turn signals work

and the truck drives and runs like a champ

hope that provides a little more info for ya

Grossey

 

[DBF]

Electrical problem

I don't see anything else that would do what you have, so it's got to be the fusible link that blows out when something downstream (off Fuses 4, 5, or 6) takes a lot of current.



This link is located just off the A0 splice, under the hood, driver's side, above the fender, between the forward grid heater relay and the skin of the truck.



I've scanned some pages from the FSM to send you, but they're too large to post here. Do you have an email address that will handle large files (600+kbytes, about 3 or 4 of them)?



If you can find this splice, where some number (7?) of fusible links come off a 6guage black wire to links to mostly 12guage wires, that's the place. The link that is open is the 18guage grey one that leads directly into a 12 guage red/white wire, the only red/white wire in that bunch.



That red/white wire runs off thru the bulkhead connector (pin 1) to the fuse block to Fuses 4, 5, & 6, and to the headlight switch. So that thing rears its ugly head again, because if the link is blown open, something caused it to open.



I'll wait for your reply and send more data there.



DBF

 

[GGrossman]

fixed

Thanks for the help

Fuesable Link by The grid heater like you said

Corroded in half didnt melt.

Thanks for the help!!!!!