There is no relay on trucks of this vintage.

What there is...TWO different flashers. T/S flasher plugs into the back of the instrument cluster.

H/D 4 way flasher (has a louder CLICK) nestles into a bracket that is retained to the backside of the dash w/a screw.

H/D flasher also used as the T/S flasher with trailer tow and for people that are hard of hearing.

See parts catalog pic:

 

Thanks ND.

 

Thanks for the info crazedfox, once I've got a little bit of time to myself I'll work through what you've suggested and see if I can make some headway with it.

But, here's a bit more information to see if this makes any more sense or can help with tracking down the issue. Driving the truck today with my wife following in the car, she noticed that my rear lights were flashing while I was driving and when braking they would get brighter and stay on, and when turning, the right one would flash and the other light would go out.

Now I'm thinking about it, the driver's side tail light bulb burnt out (or so I thought). I replaced the bulb BUT I'm thinking that I might have put the wrong bulb in :? Would this cause the issues that I'm experiencing here? I'm thinking that I've put a single filament bulb in and not the double filament that it should be. Might try changing both the rear bulbs and see if this makes a change. Just to check, I need the 1157 Bulb for the rear lights and turn signals.

AND another thing, when I push the brakes (with ignition OFF), I can hear the flasher going in the cab AND the blower motor seems to pulse. I think this is all linked in together with the same issue, and when I can figure out what that is I might be good!

Just to clarify, where is the bed grounded to the frame? I think it's going to be worth me making a couple of new grounds between the bed and the frame for the rear lights and just make sure that all is good in that respect.

As always, any and all help appreciated and welcome!!!

 

UUUHHHHH, maybe try replacing the plug end that was drug? fused, burned touching wires in the trailer plug unit?

 

What???
Try to clarify please, your not making any sense.

 

Kierobi:
This an interesting issue.

The rear bulbs consist of_
#1157 bulb- turn/brake & running lights.
#1156 bulb- reverse lights.
Side-markers is usually are a #194.

Front bulbs consist of_
#1157 bulb- turn/brake & running lights.
& side marker is same as rear side marker.
____

The bed is grounded through the bed Mounting-Bolts.
& you only need to attach your new extended ground to frame on the drivers-side.

The bed wire harness has shared ground, so no need to put a extended ground on both sides.
____

I'll need need your Model, & Year to go through my schematics,
to properly solve this oddity back-feed your blower your having.

The blower shouldn't surge when brakes are applied,
it isn't supposed to even be on when ignition is off & key removed.

 

[QUOTE=HeavyDinSC;.
I think I may have created this problem by unexpectedly dragging my trailer pigtail connection a few weeks ago.

UUUHHHHH, maybe try replacing the plug end that was drug? fused, burned touching wires in the trailer plug unit?

What???
Try to clarify please, your not making any sense.


Better?

 

[QUOTE=TeachNlive4ever;15642032][QUOTE=HeavyDinSC;.
I think I may have created this problem by unexpectedly dragging my trailer pigtail connection a few weeks ago.

UUUHHHHH, maybe try replacing the plug end that was drug? fused, burned touching wires in the trailer plug unit?

What???
Try to clarify please, your not making any sense.


Better?[/QUOTE]

_
A little.
But, the form of your english is atrocious.
-
As for the trailer-pigtail that was dragged, it was replaced.
But it didn't resolve the issue.
.

 

My apologies, Please accept that, as any more explaination I could make, will sound smart A.
I did not read that you had replaced the pig tail.
Sense your last transmission, did you make any head way in resolving your issue?

 

OK doke, so I bought a pair of #1157 bulbs to replace both of the rear turn signal/brake light bulbs to see if this clears me of the problem I'm having with the weird blinking I'm getting when driving. From what you've said it would make sense because with the single filament bulb, I would be grounding across both circuits and potentially closing them. Hence the weird blinking.

Really sorry, I should have clarified the year and model when I chimed in. I'm driving a 1976 F250 Ranger XLT/SuperCab in which the POs have done an awful lot of wiring butchery and that's why I'm having a load of problems (if you check out my other posts, you'll see what I've been coming across in the 6 months I've owned the truck). One of the biggest issues being a connector block in the driver's footwell that had all sorts of wiring running to it and from it and I'm still trying to get that straightened out...

The blower pulsing thing is only when the ignition is OFF (doesn't do it in ACC/ON position) and the blower motor doesn't run constantly, it just pulses. When I take my foot off the brake it stops. It's weird, but hopefully I'll find an end to it.

I figured the bed grounded through the holding down bolts, but I wanted to be sure there wasn't an additional strap or something somewhere I could check. I am going to be adding in a grounding wire sometime in the next few days to try and "clean up" the ground connections for all the rear lights and that hair spray tip you put me onto will be used for everything exterior from now on!

Going to put the new bulbs in and I'll see what's what after that. Will post again later on when it's done...

 

OK, so I just changed the bulbs in the rear turn signal/brake lights and it seems to have done the trick. I won't know for sure until I drive around with my wife following me again, but from the "driveway testing" I did, it looks like a solve. It was interesting to note that not only had I put a single filament bulb in on the driver's side, the passenger side despite being a dual filament was also the wrong bulb (2357 or something like that). Now I've got "dull" constant lights when running lights are on and "bright" flashing lights when turn signals are on, and NO flashing randomly in either state (I think, like I said I'll double check when the wife's not busy).

BUT, I do see the sense in running the new ground cable on the driver's side, so I'm going to go ahead and do that anyway. Probably, I'll run the ground from an existing ground (i.e. rear lights ground to bed), down to the bed somewhere easy for me to put in, and then clean up all the grounds to the bed that I can find. Hopefully that'll clear some of the gremlins.

Interestingly, after I did the bulb swap/dance, the pulsing blower and flasher isn't happening anymore, but again intensive testing will ensue to make sure it's a gone problem...

 

Alright, so just went on the test drive with my wife following and it looks as though on the whole, the brake lights/turn lights issue is resolved. The only problem I've got now is that the turn signals in the instrument cluster stopped lighting up/got real intermittent in when they would come on and flash. Also noticed that when I put the hazard lights on, they would flash when the brakes were OFF and stay on when the brakes were ON based on the turn signal indicators in the dash cluster.

Reading back through what NumberDummy posted about the turn signal flashers and now am I correct in saying that I'm supposed to have TWO flashers? One for the turn signals and one for the hazards? I've had that instrument cluster out a number of times and I'm almost certain I've only ever seen one. It is on the left hand side of the dash as you're looking at it and it's hanging loose, so it probably is the one that's supposed to be clipped to the back of the instrument cluster.

Could I be right in thinking that faulty flasher units could be the cause of my problems? I'm going to run down to Advance and get two new flasher units and replace them (both if I can find the other one) and see what happens after that. If they don't fix it, it's always better to have new ones in there, but I'd really like to have a handle on this... The other thing I should maybe point out is that my Hazard lights switch is on the column under the shift lever and not in the dash as shown on NumberDummy's diagram, if that makes any difference?

 

Kierobi:
Ok, lot to absorb here.
-
Alright, when you have the hazards on the brake is supposed to override & make them brightly solidly lit.
-
As for turn, only the side that is marked will blink & the opposite will be solid.

(example: if you turn on say; the left turn-signal then hit the brakes the left will blink & the right will go solid bright.)
-
Yes, you have 2 flasher cans/cylinders.
Your "turn-signal" can is the one hanging down from the left/drivers side behind the cluster.

The "hazard" can is off to the right usually somewhere between the cluster & radio/climate controls.
So when you got the gauge cluster out, look to the right.

It usually will be mounted to the support brace between the radio & the gauges.
Sometimes you have to remove the radio or climate controls to find it.
But it's supposed to be there.

As for the "hazard"-switch location.
Yes, it's supposed to be mounted in the column, it's part of your turn signal switch assembly.
Only the big-boy "heavy-duty" trucks had the hazard switch in the dash.
-
Good luck.

 

I'm not quite sure how so many of you are able to provide clear and concise answers based on my incoherent ramblings, with the added eloquence of a drunken baboon, but I love it!

I managed to find BOTH of my flashers after a bit of searching around. Both the turn flasher and the hazard flasher were on the left hand side of the dash. The one I could see previously turned out to be the Hazard flasher (could feel it clicking when hazards on) and the turn signal flasher was found tucked up underneath the lights and wipers switches, with a dab of glue gun glue holding it to the dash.

While I had the cluster out, I noticed a wire had come loose where it had been repaired with a crimp. Cut the crimp out and did a better repair grafting in a length of wire and noticed my intermittent hazards problem disappeared. The wire is green/black stripe and goes into a black "y-piece" connector with a yellow/black stripe wire. When I was messing about with this wire, I was also losing the interior lights and the turn signal lights on the cluster, so I'm guessing that's been a big part of some of my issues.

Replaced the flashers with the "heavy duty-loud click" type ones from Advance and cut out the crimp repair on that wire and did a proper one and it. Tried my lights when it got a bit darker and found that when I put the lights on (pull the switch), the passenger side rear light comes on, but the driver's side doesn't. Also put brakes on with lights on and driver's side light doesn't light. Turn the lights off and the driver's side light comes on but not the passenger side. I thought it could be a grounding issue so I cleaned up the ground for the driver's side stop and turn lights, but the lights are bright when on and it made no difference. The side marker lights are coming on, so I should have supply back there.

Honestly feel like this electrical issue is driving me nuts right now! I seem to make one step forward and then another back, turning up something else when I do! Hoping somewhere in my ramblings, you can make sense of it and offer some advice...

Thanks for clarifying the whole lights when they should be blinking and when they should be solid thing for me as well. I wasn't sure at all and I think that was causing more confusion than helping me!

Thanks for your help crazedfox! Looks as though you're the go-to guy for the electrical side of these old trucks!

 

I would go and study the truck wiring schematics and confirm at various points of the wiring to verify that it matches the schematics.

Looks like your on the right track with this, fixing PO's butchered hackery. I like soldering the wires, and sometimes do the easy soldering with those heat shrink solder crimps. Also, I like pull all connectors and cleaning those up and stuffing them with silicon dielectric grease or compound to prevent further corrosion. Not sure what one can do if the wire to crimp connector is bad, but I suppose one can cut and crimp in new connectors and then dielectric grease them. You could also use White lithium grease for extra protection from the elements. Makes a mess, but works.