Brake light and turn signal trouble

[mr1030]

Hello all. My 1971 F250 was at mechanic for some engine work the other day. Got it back home and noticed that the brake lights do not work. Nor do the turn signals or the hazard lights. These worked fine prior to the stay at the mechanic. The tail lights work properly. and so does all the rest of the lighting as far as ive noticed. The 20A fuse is blown and new ones inserted blow immediately. The work on the engine involved pulling the motor. From reading other posts on the forum, I would figure that the culprit was the turn signal switch as i believe the brake lights are routed thru there as well? I'm just wondering since this seemed to happen as a result of the truck going in to the shop, how the engine work could possibly result in possible switch problem. Any ideas of another likely cause? I want to give it some thought before I just go and buy a new switch.

[FORDification]

I'd start looking very carefully at the wiring harnesses that run along the top of the inner fenderwells. Since you've recently had the engine in and out, it's possible (probable) that something got dropped or rubbed on one of those harnesses, and now there's a bare wire (or two) that's grounding out, blowing the fuse.

[basketcase0302]

mr1030,

These worked fine prior to the stay at the mechanic.

If you have a good relationship with them I'd take it back and request them to fix it!

Like Keith said about the harness:
I'd look real hard at the wiring there.
No-doubt had the hood off and probably were standing on the same inner fender to guide the engine back in.

Basketcase

[Joshpow]

I agree with the idea of a pinchedwire in the harness. The brake/turn wires go down the firewall and back so one could have gotten pinched easily. I wouldn't think a bad turn signal switch would cause the hazard lights not to work. Just my .

Hope you find the cure soon.

[mr1030]

Thnx for the ideas. Its raining buckets today, so i'll have to wiat for some clear weather to check it out, but i'll let you know what I find.

[Underdog97]

Another possibility here is where the wires for the rear lights plug into the harness up front by the bellhousing, Often when an engine is removed or replaced they can get pinched inbetween the engine and transmission and cause a direct short out.

[Joshpow]

Underdog97 is correct. There is a plug there. Be sure to check that too. Also try the plug at the back under the tailgate area if all else fails.

[mr1030]

Thnx for the ideas guys. My next door neighbor is a mechanic and a couple days ago we we tested pretty much all the wiring. There was definitely a short, and all the wiring checked out ok. We pretty much narrowed the short down to the wiring btwn the firewall and the turn signal switch itself. So i'm gonna pull the wheel and check out the switch, and try to get a spare switch and plug it in and see if it fixes everything. I'll let you know what happens.