High mounted stoplight and rear side marker lights not working (Page 1/2)
4evrnyt JUL 18, 05:49 PM
I noticed that when I turned on my lights my rear side marker lights were not coming on. I replaced the bulbs because both looked burned but they still didn't work. I also noticed that my high mounted stoplight is not illuminating when I put my foot on the brake.

Obviously I've got a bad ground somewhere. Any ideas on where to start?

Thanks!

88 Base model
4cylinder
T-tops
theogre JUL 18, 06:46 PM
Some 88 grounds to frame and wiring overall are different for somethings then early years but 1 or 2 bulbs not working often is problems w/ the sockets.
(Like Rear lights are not grounded to frame behind rear quarter like older Fiero.)

See my Cave, Lighbulbs for one example.

194 and related type often have iffy sockets w/ metal not hitting bulb wire(s). Try bending the wire on bulbs out a bit to see if that is happening.
Plus the socket metal should hit both sides of bulbs but "rust" can rot the socket or metal cracks over time causing problem.
Even if bending a bulb wire helps, Often will need to replace the socket if true.

Can check wires to them w/o cutting.
Use a sharp needle thru insulation. Coat wire w/ silicon grease after to keep out water.
Make sure the needle isn't plastic coated etc to stop a meter or test light to work.

Check that a socket or + wire gets power when it should be on.
Check ground to frame should near or at Zero Ω

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

4evrnyt JUL 18, 10:17 PM

quote
Originally posted by theogre:

Some 88 grounds to frame and wiring overall are different for somethings then early years but 1 or 2 bulbs not working often is problems w/ the sockets.
(Like Rear lights are not grounded to frame behind rear quarter like older Fiero.)

See my Cave, Lighbulbs for one example.

194 and related type often have iffy sockets w/ metal not hitting bulb wire(s). Try bending the wire on bulbs out a bit to see if that is happening.
Plus the socket metal should hit both sides of bulbs but "rust" can rot the socket or metal cracks over time causing problem.
Even if bending a bulb wire helps, Often will need to replace the socket if true.

Can check wires to them w/o cutting.
Use a sharp needle thru insulation. Coat wire w/ silicon grease after to keep out water.
Make sure the needle isn't plastic coated etc to stop a meter or test light to work.

Check that a socket or + wire gets power when it should be on.
Check ground to frame should near or at Zero Ω




A scouring of the leads on the socket brought the side markers back to life but the high mounted stop light still has a problem. I confirmed the socket receives 12 volts when my foot is on the brake pedal.

[This message has been edited by 4evrnyt (edited 07-18-2019).]

4evrnyt JUL 19, 03:48 PM
I clipped the negative wire and ran it to an engine block ground and still no go with the light. I guess if the ground is good and it's receiving voltage the only thing left is to replace the connector??
theogre JUL 19, 04:41 PM
Have you try a new bulb? Or at least Ω test this one from the pins in the base? This Bulb can break in a few ways but look ok.
bulb is 889 27w
Do Not use others that are 35W to 55W or you can melt everything quickly.

Note that if you touch halogen bulb glass you need to clean w/ alcohol or glass can pop/shatter.

Could socket not connecting w/ the bulb too.
Metripak plugs are easy to damage by owners and others.

maybe socket is metripak 150 PTS in my Cave, Weater/Metri Pack notes and many try treating as Weather Pack and damage them. Is a pain to remove even w/ exact GM tools.
Even if is back loading metripak is often harder then weather pack.

[This message has been edited by theogre (edited 07-19-2019).]

4evrnyt JUL 20, 08:05 PM

quote
Originally posted by theogre:

Have you try a new bulb? Or at least Ω test this one from the pins in the base? This Bulb can break in a few ways but look ok.
bulb is 889 27w
Do Not use others that are 35W to 55W or you can melt everything quickly.

Note that if you touch halogen bulb glass you need to clean w/ alcohol or glass can pop/shatter.

Could socket not connecting w/ the bulb too.
Metripak plugs are easy to damage by owners and others.

maybe socket is metripak 150 PTS in my Cave, Weater/Metri Pack notes and many try treating as Weather Pack and damage them. Is a pain to remove even w/ exact GM tools.
Even if is back loading metripak is often harder then weather pack.




Tested the old bulb for continuity and it passed but I replaced it anyway just to double rule it out and the new one didn't work either.
Spadesluck JUL 22, 04:57 PM
I honestly think the wiring for the 3rd brake light finicky. I have a constant low power being supplied to mine. I plan on messing with it after I take the headliner out again.
4evrnyt AUG 01, 04:45 PM
Well I'm totally flummoxed.

Replaced the connector and still the high mounted brake light will not illuminate.

Recap: I've checked ground and have even tested it with a different ground that I know is good. I've confirmed that it's getting 12v when I have my foot on the brake pedal. I bought a new connector, confirmed it worked by hooking it's leads up to the battery and it too will not illuminate when it's connected to the stock hot wire for this bulb.

I know the ground is good and I've confirmed it receives the proper amount of power when it's supposed to, what in the heck is making it not work?!?!
theogre AUG 01, 06:22 PM
Not sure either...

12v w/ engine running or not?
not the 12v is good.
Running should be ~ 14.7 volts

Try Jump the light blue wire to the orange wire at the brake pedal switch.
There's 2 connectors under the dash I think w/ same light blue wires. Both are hard to see hidden by the dash etc. Both are left side but not exactly where or how to get at them for 88. older cars can see better removing left speaker.

May have 12v etc but any/all may have problems and not passing enough current to light the bulb.
Especially Switches/relays can wear out or burn connections/contacts and can see 12v but have too much resistance and bulb(s) can be dim or just won't light.
4evrnyt AUG 04, 09:44 PM
It's 14v with the car running.