turn on my headlight and the truck dies!! WTF

[7tcutty]

87 fuel injected half ton chevy no power anything not ever air conditioning.

this is the first time ive had a chance to look at this truck

when it starts it runs pretty good needs tuneup bad! but
if you turn the light on the truck cuts out and will not start.

the truck will turn over but there is no power to the fuel pump to start the truck. if you wait (unknown amount of time) it seems to fix itself and the truck will start and run..

i did notice even if the truck is turned off if you turn on the lights you get nothing! also the dimmer switch in the column does not work..

has anyone had this prob before? and where should i start looking fr my fix?

thanks allot
karl w

[86 GMG]

my guess would be start in the steering column due to dimmer not working and ignition switch and all is in the column best of luck and keep us posted on the problem you find sorry i cant help any more than this

[Paso76GMCstepper]

I assume he means a "short" I also agree. I had a headlamp that was shorted out over the filiments and when I turned on the lights "BAM" truck died. You might want to look around its definitly a short somewhere.

Headlights are cheap, so it a dimmer switch. Check the plugs going the headlights. Also it could be a running light bulb. I replaced all my running lights, brake lights, and stuff when I had the cooked headliamp.

Just a thought

[7tcutty]

well i took a bunch of stuff apart today this is what i found. there is no power to the headlight switch ANYWHERE there is also no power to the dimmer switch. on the fuse block on the side closest to the driverside fender there are three fuses non of them have power to them and the fuses are good!..
now i am completly stumped . my guess is that one of them controllls the fuel pump and horn.. i cant locate the fuel pump relay either to try and hotwire that. and i have unplugged one of the lights still no power to it i have disconnected the battery to no avail.. this truck is soooo muddy i just want to get it to run so i can take it to the car wash and spend 20$ powerwashing the muck offn it.
thanks for the help guys PLEASE KEEP THE HELP COMMING i am STUMPED :BANGHEAD:

[Paso76GMCstepper]

Well did it run ok BEFORE the MUD. If it did and doesnt now I would say you have a major electrical problem brought on by essesive moisture (MUD)

I burnt up a whole trucks wireing once getting out of a 4x4 trail that was laden with mud.

[86 GMG]

check the connections under that brake booster where the outside wire harness meets the inside harness it may be caked up with dirt and corrosion i think it is bolted together with a single bolt

[7tcutty]

it did the same thing before i caked it with mud.. i am going out now to tear some more stuff apart i will check that part under the booster! thanks for all your help guys!!!

[7tcutty]

I FIXED IT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

well i started from the beginning and went directly to the starter. turns out there was some SHODDY wiring done there by a P.O (previous owner) they only way i found that was because is used my didgital voltimeter and found there was current at the light switch.. so i replaced the bad wireing and fusible links (sodderd and heat shrunk wrapped) and then hooked everthing back up and tested the light switch 12+ volts hit the key and he fired right up!!! lights work horn works everthing works!!!

THANKS TO EVERYONE THAT HELPED ME OUT ON THIS I REALLY APPRECIATE IT..
i doused all the electrical connections with corrosionx HD to make sure that they have good contact and wont corrode and the trucks good to go!! NOW to change my ebay add :biggrin:
thanks again
karl W