Electrical Problems - Advice sought (1 Viewer)

[dx379]

Guys,

This is on a 1970 40.

My turn signals were working and all of a sudden quit. Does anyone have a picture of the location of the relay I have read about?

My tailights work. However, my passenger brake light keeps blowing. They are a dual filament bulb right? - so what would make just the brake light part of the filament blow and not the whole brake light? Any ideas where I should start?

My headlights stopped working. It turned out the connection of the headlight to the fuse block was in bad shape. I relocated it to a different fuse and worked fine. Last night they started working intermiitently. I tried moving the headlight wire around and it didn't do anything...

Any suggestions?

Jonny

 

[jgray]

Lots of good info here...

Coolerman's Electrical Schematics and FSM File Retrieval

 

[gsdog2]

I have a '72 and mine stop working every now and then,,,I just wiggle the hazard switch and they work again.....they are connected somewhere in there I guess. See if that works.

 

[dgangle]

sounds like a new aftermarket wiring harness is in your future

 

[bsmith123]

lights

You could try disconnecting all of the lights and see if you can get them working one at a time until you run into the problem ---if one of the lights is causing the prob this could work

or bypass all the wiring with a hotwire and see which ones will work and which ones wont

then start isolating the prob based on the results of those two tests

for the brake bulb try swapping the bulb with the other side and see if it works or blows again

the idea is to start narrowing it down a little


are the rear side lights working?--they appear to share power with the rear combo light in the 71 schematic disconnect them and see if the combo lights work---also check the actual rear light grounds and make sure they are good. A short in the side light downstream from the rear combo light may also cause it to draw too much through the light and blow the bulb pretty much the same way a short heats up a wire


I dont know if any of these are common I just spent a few secs looking at the schematic

Isolating out parts of the lighting should be a good narrowing technique though or at leas tell you it is not at the light or terminations themselves

 

[Coolerman]

OK first answer: the 1970 has TWO flasher relays. One for the hazard and one for the turn signals. While I don't know exactly where they are located (I have a 1971 with only one relay) they look like a long round metal can that's bolted to the firewall. Try the hazards, if they blink follow the click to the hazard relay. The other relay you locate will be your turn signal relay. You should be able to swap the two relays to determine if that is the actual problem.

Now go to each turn signal light housing. Take it apart, clean all the rust out of the housing and socket. The housing MUST be grounded for the bulbs to work properly. Since this is a piss poor design I would highly recommend you make a connection to the housing with a separate wire to a ground on the inner fender. See here for how I did that to the front housings. Turn Signal Ground Mod <<<<<< This is a link!!! Click it!

The passenger side brake light element blowing like that is a mystery. However the bulb elements will break if subjected to repeated harsh blows while on. Make sure your light housing is bolted down firmly and the brake light socket is not loose in the housing. While in there clean everything up. Remove all signs of rust from the sockets. Ensure the housing is grounded properly. A bad ground in the lighting circuit is the #1 cause of problems.

You really need to pull your fuse panel out of the truck completely after making a drawing showing what color wire is connected where. Use the schematics you can download form the link above to see what size fuse should be in what position in the panel.
Once the fuse panel is out of the truck, use a Dremel tool with a wire wheel to clean every single connection point, especially the fuse clips AND the ends of the fuses. Use needle nose pliers to bend the clips in slightly so they make a better connection on the fuses. Now clean the ring terminals on the wires that were going to the fuse panel and finally put it all back together.

On the headlights: First go here for a harness identification page: 1971 Electrical Harness <<<<<< This is a link!!! Click it!

Unplug the socket from the back of the head light. Look inside the connector. If it's all corroded, you need to take each wire out of the socket and clean it up. The wires are released from the socket by inserting a thin screwdriver into the notch and pulling the wire out. Do one wire at a time! They are brass so clean easily. Put some dielectric grease in the socket and plug them back up. Follow the harness back to the three wire harness plug on the inner fender. Unplug that and look inside. These do not come apart so you have to clean them the best you can. I use a very small Dremel wire brush to do this.

You also need to clean every battery/alternator/frame ground completely and reassemble.

Once you have done all that, come back and ask us specific questions about trouble shooting. I bet you will fix your problem if you do all the above...

Good Luck!

 

[MarcoPolo]

Just replaced my hazard and headlight sw's because of similiar prob.
Only have the left front not signaling now and in the process of chasing it down.
My prob turned out to be both sw's.

 

[Blacksunshyne]

I just went thru this same problem. My 1970 has a hazard relay and a seperate flasher relay. The hazard relay is located on the fire wall, driver's side, to the left of the clutch and brake if you are looking at the firewall. The turn signal relay is located on the firewall on the passenger side of the cab.

I ended up putting the hazard relay in place of the turn signal relay (since my hazards worked). I ended up finding out that I have a bad flasher relay. But this resulted in the hazard relay having a little 'ticking' noise, almost like a signal was on, even when it is not. So, i will continue to chase that problem.

These relays are self grounding, so don't make my mistake and buy a plastic bodied one, or wrap a metal one from the parts store in electrical tape to make it fit into the holder.

Now I am looking for a flasher relay for a 1970 FJ40. Seems they are no longer available. Anyone have any ideas on where to find such an animal? Or what I could use in place of the OEM flasher?

 

[Vicm]

I just went thru this same problem. My 1970 has a hazard relay and a seperate flasher relay. The hazard relay is located on the fire wall, driver's side, to the left of the clutch and brake if you are looking at the firewall. The turn signal relay is located on the firewall on the passenger side of the cab.

I ended up putting the hazard relay in place of the turn signal relay (since my hazards worked). I ended up finding out that I have a bad flasher relay. But this resulted in the hazard relay having a little 'ticking' noise, almost like a signal was on, even when it is not. So, i will continue to chase that problem.

These relays are self grounding, so don't make my mistake and buy a plastic bodied one, or wrap a metal one from the parts store in electrical tape to make it fit into the holder.

Now I am looking for a flasher relay for a 1970 FJ40. Seems they are no longer available. Anyone have any ideas on where to find such an animal? Or what I could use in place of the OEM flasher?

You should be able to buy a cheap turn signal flasher from your auto store.
I have one in my 40 . Just don't buy a haz flasher .
If you don't mind it , you could also buy an elsectronic one.