help with brake light switch

[conesare2seconds]

Hi, everyone. This is for my other Corvette - 88 Callaway Twin Turbo. Hoping the brake light switch is the same and someone can offer pointers.



Recently found the brake lights are inop, not sure for how long as there were no inspections in AR when I lived there.



Visual check of switch shows there is an unused socket adjacent - anyone know what it is for? (Sorry if photos are upside down. They look fine in photo viewer.)


9781


One photo in particular appears to show a crack in a joint of what I presume is the switch. Am I on the right track thinking this could be the source of the problem?


9782


Not sure where to start and would appreciate suggestions.



9783
9784

[WVZR-1]

Assuming you've checked the STOP/HAZARD fuse? That would be first check. Do the HAZARDS work? Does the CHMSL work or have you lost 'ALL'? Julian date on SLS 7317 certainly hints 'original'.

A 'local' purchase of a GM 25529860 (equivalent) should be inexpensive. NAPA likely has 2 choices 'on the shelf'.

If ORANGE @ SLS is powered/HOT when checked with test light - switch time.


***Male spades I'd think meant for A4 TCC

[conesare2seconds]

Thanks for the reply and the part number. She has tail lamps but no brake lights at the tails or the CHMSL. Hazards are functional.


I pulled the switch and found something unexpected: a thermistor (I think). Anyone have any idea why it would have been added?



The switch is quite warm, no telling how long it has been that way but I don't think that should be happening.



9807

[WVZR-1]

Thanks for the reply and the part number. She has tail lamps but no brake lights at the tails or the CHMSL. Hazards are functional.


I pulled the switch and found something unexpected: a thermistor (I think). Anyone have any idea why it would have been added?



The switch is quite warm, no telling how long it has been that way but I don't think that should be happening.



9807

Capacitor is to be expected. Should be 2. See any FSM @ 8A-110 but for an '88 it's only in the supplement. I don't believe the FSM shows them. Do you have both the '88 FSM and also the 8A supplement that's 25 or so pages.

[WVZR-1]

The 8A-110 in the FSM seems to be missing this. This is from the '88 Supplement.


9808

[conesare2seconds]

Thanks. I have a 91 FSM + supplement, can’t read a wiring diagram though. Thanks for the info on the capacitors. I’ll order a new switch.

[Z51JEFF]

Keep in mind once the switch is unplugged the brake lights will come on,at least on my 91 they do.

[conesare2seconds]

Replaced the switch and got an unexpected result:
- CHMSL works,
- left inboard and outboard brake lights work,
- right inboard and outboard brake lights do not.

The right side turn indicators work and the right side illuminates when the hazard lights are on, so the stop lamp bulbs don’t seem to be the problem. Regular tail lamps illuminate fine on both sides. Also notable, the brake lamps do not come on when the switch is removed. Any suggestions before I turn it over to a shop? I know zip about electricity but will try anything else I could have overlooked. Maybe a dirty connector at the switch?

[Hib Halverson]

Your problem is likely in the harness that runs along the right side of the cargo area and goes to all the rear lighting, but it's downstream from where the harness running up to the CHMSL breaks out.

You need to check all of the rear bulb sockets, wiring and grounds inside the body behind the rear fascia.

[WVZR-1]

Check 1st the longer directional switch connector right side of column. All stop and directional other than CHMSL pass through that connector and the directional. The white wire from the SLS I believe goes to terminal P of that connector.

You had HAZARDS originally and I'd think it very unusual for your issue to have moved to a different vicinity of the car harness.

Directional connector is 11 terminal and in your '91 FSM 8A-201-20 is identified well. Also in your '91 FSM you can check 8A-110-0 for appropriate references.

[conesare2seconds]

Thanks for the helpful responses. I’ll get back under the dash and have another go at it.

[conesare2seconds]

Well, in a victory more for luck and not giving up too easily than for my electrical expertise, we now have full brake lights. I checked out the FSM (spot on references, thanks again) and fiddled with the connectors as suggested. What made the difference? No idea, but take the victories you get. Appreciate everyone’s input.

[WVZR-1]

Well, in a victory more for luck and not giving up too easily than for my electrical expertise, we now have full brake lights. I checked out the FSM (spot on references, thanks again) and fiddled with the connectors as suggested. What made the difference? No idea, but take the victories you get. Appreciate everyone’s input.

I'd think the 11 terminal to the directional was only loose. The 'latching' is centered and frequently it's not latched by many. I'd not worry and if you've a similar situation ever > GO THERE FIRST!!

Have you ever done a directional switch, column repairs or had the column removed for any reason.

[conesare2seconds]

No known history of directional switch or column repair/removal. The microfueler is wired in nearby and the ALDL relocated, so the wiring in this vicinity has been “touched”, perhaps the source of the loose contact.


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