Tail Light Gremlin, Part 2

Matt G

Matt G

Member
Here's the deal: 74 Scout 2 with all stock wiring. The rear lighting harness was butchered fairly bad at one point by a po for a trailer light hookup.

'bout a week ago I lost the left brake light, but the left blinker (which uses the same bulb filament and same wire to the tail light housing) works fine.

Mayben helped me work through some grounding issues I had back there which have now been rectified by running new ground wires from both light buckets to the body. Everything now grounds great and the left brake light worked again for a couple days. But I just lost it once again - blinker still works fine, as does the right brake light (actually, all other lights on the rig work perfectly).

So, novice electrical chump that I am, I deduce that the problem must be on the power side of this circuit, not the ground side. If I understand my wiring diagram correctly (big if) the brake light circuit runs from the switch on the brake pedal to the big "fan" connector on the steering column. There it merges (through the turn signal switch?) with the circuit for the blinker, and both signals then use the same wire out the bhc and back to the tail light. Is that right?

If so, the problem would seem to be with the turn signal switch itself? Since the blinker circuit works perfectly I deduce that there's no connection problem between the steering column and the light bucket. And since the right brake light works perfectly I deduce that there's no problem between the brake light switch and the fan connector. So it must be the connector itself? That connector and the ignition switch above it are uncharted territory for this novice.

Any advice?
 
Only thing I can think of is testing the brake light wire for current into the connector and for current out of the connector (engine running; brake pedal depressed) for the "brake wire".

You can take the connector apart (careful of 35 year old brittle plastic) and check for corroded pins (clean with "electrical cleaner"); a wire that came loose from a pin in the connector.

I haven't had my IH connectors apart, but the "pins" / "spades" are held in the connector by a metal spring clip. You can release / remove the pin from the connector by using a very small thin blade screw driver. You "release it"; looking at the pin in the connector (in my experience) -- if you look real close you May see the groove for the clip (in the "center"). I would only remove one wire at a time -- because that is the only way I would be able to get it back together correctly.:icon_rolleyes:

I doubt the "brake wire" goes into the turn signal switch because I think there is only contact when the lever is moved. The turn signals work in conjuction with the turn signal flasher -- "gizmo" (small "canister") that makes the lights flash -- it is up under the dash (at least it is on my t/a).

If you find a "too damaged" "pins" / "spades", you should be able find a matching new one at a good auto parts store. You can find a good wire crimping tool in the electrical section of most hardware stores -- if you do not have one.

Hth
 
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Yes the problem is in the turn signal switch itself. From the brake light switch the circuit runs to a contact in the ts sw. When the ts is activated it disconnects the bl feed from the activated side and connects it to the circuit leading from the flasher. Since the ts works on that side the circuit from the sw through the "fan" connector to the tail light assembly are good. Since the brake light works properly on the other side the brake light sw and the power to it on to the ts sw is good. Leaving the only point where the power could be "lost" is in the ts sw itself. While not a really common failure I have seen it numerous times, in fact I am expecting a new ts sw for a freightliner tomorrow which has this exact same issue.
 
X2 with eric, I bet if you hold the brake down an wiggle/move the ts it will probably come on. I get that symptom from time to time on my 75 Scout.
Ron
 
Thanks for all the feedback gents. Eric/ron, thanks for the confirmation of my thinking. I wanted to think this thing through before I started throwing new copper & parts at it or taking 35-year-old fan connector apart (which looks fine from the outside).

Adding further evidence to the ts-switch-is-the-culprit theory is that my ts lever has always been pretty loose & sloppy. It works, but the po had messed with it already at some point. Looks like I get to buy one of those steering column pressure plate depressor thingys and a new ts switch - which is fine, 'cause it needs to be done sooner or later anyway.

Now, if I pull all this off correctly on my own it'll be final proof that Mike is a first class instructor!
 
I forgot about the "damage" I May have created when that 4lb. Hammer hit the wrong Mark while doing the mod on the steering column support! Ya remember? When the signal lever disappeared?

If ya keep wiggling the lever/switch right now, I bet the issue comes and goes.

So the switch needs to be replaced which is simple...but ya will need to pop the steering wheel off again and get one of those lock plate depressor tools I described to ya at the time when the wheel was off. Harbor freight has both tools to add to your arsenal and ya can move the steering wheel one more "tooth" and hopefully re-center...the other direction!

Ya don't pull the entire harness through the column, ya replace only the upper component and splice the "repair" switch segment in.

But...if this hadn't happened, ya would not have found the ground issues in the light buckets either!
 
Hey, I was going to cover you 100% in public! What happens at your shop stays at your shop! I don't even remember a 4-lb sledge hammer... :ihih:

in all seriousness though, you probably remember that once we got in there we realized that the ts switch had been monkeyed with before. And my ts level was always real sloppy - I just ignored it 'cause it worked and there were always other things to spend time and money on. But this job has needed doing for a long time now, so it'll feel good to actually get it done.

Are the lock plate depressor's pretty common at the parts houses? I would assume that they would be since it's a GM column.
 
I was able to retrieve your vmail from last Friday, but couldn't call ya back from the dunes trip as cell service came and went constantly.

Most parts houses have a couple of different lock plate tools, one is real cheezee and prolly won't make it through one application! The other is much better quality though it's still nothing to crow about...but will work for ya.

Since I already popped your steering wheel off...twice!...then it will extract easily with the hf steering wheel puller set, that is a tool you will use for other things in the future!

The part you described on the phone is a replacement "cam" for the turn signal switch. That is the part that is related to your original problem regarding the funkee actuation of the turn signals. The switch component is below that cam segment:

turn signal switch - Scout II built prior to 5/10/77 and 74'-75' pickup and Travelall - International Scout parts

Actually...if ya take it apart for inspection, you May find the switch segment is ok, it's the cam that is messed up...just an idea to look at before spending buckage for a switch in it's entirety.

Rather than fight with fishing the pigtail, I normally just splice the replacement in using the "red" butt splices like I showed ya, the ones that are the high quality nylon that are somewhat thinner in cross-section than the larger pvc-insulated items. The good ones are the ones you used for the assembly of the new instrument harness also.

Thanks for covering my tracks when I scruu up...but everyone around here knows I only win about 20% of the time! I shoulda used the wood splitting maul on the modification of that steering column support instead of that wimpy blacksmith's hammer. That way we coulda practiced windshield replacement and steering column rebuild.
 
Thanks man. I got a lock plate depressor tool that should last a lifetime. If I'm lucky that means I'll use it about 4 times before I die, but I have it if I need it more often.

I borrowed a wheel puller from a buddy so I'm going to rip the thing apart this weekend and see where the problem lies. I have a pretty strong suspicion that the plastic cam is the problem. Napa had one in stock for $27 :yikes: for a piece of plastic! Went across the street to knecht's and they had the same part for $11.

Btw, I did confirm what everyone here thought - the brake light comes back on when the ts lever is jiggled correctly. I'll let you know how it goes. Thanks for the link.
 
Well, that was harder than it should have been. Then again, this is an International.

The pressure plate depressor I bought, which fits "most foreign and domestic steering columns" didn't fit my "common" GM column. :mad2: fortunately I ran into mayben-north at the parts house - a nice old retired mechanic named jerry who had one in his shop and let me drive over there and use it. Man, if I didn't have nice old guys who know their automotive jack in my life, I'd be hosed!

Then there was a long saga of finding the correct replacement cam which I won't waste pixels on. Suffice it to say, if you're ever looking for a Scout 2 ts cam, you want a dorman 49300 kit (it even lists "ihc" on the package - how 'bout that?). And I can't believe I'm typing this, but both napa and knechts bombed and autozone (of all places) is the one that came through for me.

Pulled clips & springs off the old cam, relocated them to the new one, and got it in. Seems to work a fair bit better than it did, though still not crisp-as-new. Still, I guess it beats replacing the whole ts switch. Jerry didn't even know you could replace only the cam.
 
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Pretty much. As noted before I had confirmed that the brake light not coming on was due to the cam. When it would cancel after turning the wheel it would move far enough to disengage the blinker signal but not far enough to re-engage the brake light circuit. This was only on left turns. So after turning left I would have to nudge the ts lever up a bit and the it was fine.

Now it appears to be working properly. I've had it in for less than 24 hours so more testing is needed, but it cancels correctly after a turn and the brake light seem to re-engage. It is still just a bit sloppy, but noticeably better.

My final attempt at fine-tuning this thing is to replace the turn signal lever, since mayben and I did a custom number on the old one and it's not a perfect fit. Two parts houses had no turn signal levers on their shelves (and here I thought auto parts stores sold, well, auto parts :rolleyes5: )... So when I track one down I'll swap it in.
 
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The actual lever is an oem part...but is sometimes found in "repops" like the dorman "help" stuff. It's just a simple lever for GM, ihc, chrysler, amc, everyone who used that particular cam design.

I'll look for some today while I'm out...I find the levers broken off all the time on the junk I work with around here.
 
Matt g said:
Two parts houses had no turn signal levers on their shelves (and here I thought auto parts stored sold, well, auto parts :rolleyes5: )
Click to expand...

Not with computers and inventory tracking systems.

Parts sitting on the shelves for more than a specified time is "wasted" / "unused" money according to the "bean counters"... Particularly true of the chain stores including chain parts stores..
 
robertc said:
not with computers and inventory tracking systems.

Parts sitting on the shelves for more than a specified time is "wasted" / "unused" money according to the "bean counters"... Particularly true of the chain stores including chain parts stores..
Click to expand...

Yeah, each store had about 15 varieties of window cranks hanging on the shelf but not a single ts lever. Clerks at both stores walked over and essentially said "gee, I thought I carried those. I guess I don't."

*sigh*

still waiting for the IHOnly northwest branch to open on ernie bisio's old property in portland! :icon_cool:
 
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