Electrical issue

[east302]

@1998_K1500_Sub

I wonder if he could be getting voltage to Fuse 16 via Fuse 1 through the hazard flasher, keeping the ignition in “run”? It would require a stuck hazard button plus some internal mess in the flasher, though, I’d guess.

Pulling fuse 16 may be another way to test it?

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[1998_K1500_Sub]

I have a 98 tahoe 2wd. It has an electrical issue i can't seem to find.

A few quick questions:

- You have DRLs on that vehicle, right? Are they still enabled?

- Do you have any other lights that are acting "odd", e.g,. they don't illuminate fully, or they change in intensity when they shouldn't (e.g., turning on headlights causes the parking lights to become dim)?

 

[Donald Mitchell]

Do you have a trailer connector?

 

[ETrail Tahoe]

A few quick questions:

- You have DRLs on that vehicle, right? Are they still enabled?

- Do you have any other lights that are acting "odd", e.g,. they don't illuminate fully, or they change in intensity when they shouldn't (e.g., turning on headlights causes the parking lights to become dim)?

No, everything else works as it should

 

[ETrail Tahoe]

@1998_K1500_Sub

I wonder if he could be getting voltage to Fuse 16 via Fuse 1 through the hazard flasher, keeping the ignition in “run”? It would require a stuck hazard button plus some internal mess in the flasher, though, I’d guess.

Pulling fuse 16 may be another way to test it?

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If i turn the flashers on, they work correctly

 

[ETrail Tahoe]

Do you have a trailer connector?

Yes but i took it out, nothing changed

 

[1998_K1500_Sub]

Pulling fuse 16 may be another way to test it?

I agree, pulling Fuse #16 is a start. With that fuse OUT, it appears the the "run-on when brake pedal depressed" symptom may be eliminated.

So, why Fuse #16. Read on...

I'm sitting here staring at the schematic for the rear taillights (attached is the one from the 1998 GM service manual).

The only things that are OBVIOUSLY in common here, based on OP description and my understanding, are the brake pedal switch and the hazard/turn switch (see attached two-page diagram and my comments within).

I wonder if one of the contacts on that hazard switch has come off the plunger and lodged itself in the switch in some way, so as to make an improper connection. If you've ever seen the plunger on that switch, you'll know what I mean; there are a rash of contacts on it... and another rash of mating contacts within the body of the "hazard/turn switch".

But regardless, I agree that pulling Fuse #16 is a place to start. Do it OP, and see if the "run-on when brake pedal depressed" is eliminated.

Then, regardless of the outcome, replace Fuse #16 and pull Fuse #1 (stop/haz fuse) and see if the "run-on" is eliminated.

Please report your findings.

Replace Fuse #1 before you've forgotten about it.

 

[ETrail Tahoe]

I agree, pulling Fuse #16 is a start. With that fuse OUT, it appears the the "run-on when brake pedal depressed" symptom may be eliminated.

So, why Fuse #16. Read on...

I'm sitting here staring at the schematic for the rear taillights (attached is the one from the 1998 GM service manual).

The only things that are OBVIOUSLY in common here, based on OP description and my understanding, are the brake pedal switch and the hazard/turn switch (see attached two-page diagram and my comments within).

I wonder if one of the contacts on that hazard switch has come off the plunger and lodged itself in the switch in some way, so as to make an improper connection. If you've ever seen the plunger on that switch, you'll know what I mean; there are a rash of contacts on it... and another rash of mating contacts within the body of the "hazard/turn switch".

But regardless, I agree that pulling Fuse #16 is a place to start. Do it OP, and see if the "run-on when brake pedal depressed" is eliminated.

Then, regardless of the outcome, replace Fuse #16 and pull Fuse #1 (stop/haz fuse) and see if the "run-on" is eliminated.

Please report your findings.

Replace Fuse #1 before you've forgotten about it.

Pulling the fuse does allow the brake lights to work, just no turn signals as expected.

 

[ETrail Tahoe]

If i replace 16 and pull one, the brake lights are out and the right turn signal stays on, does not flash but left works fine

 

[1998_K1500_Sub]

Pulling the fuse does allow the brake lights to work, just no turn signals as expected.

So you’re saying the brake lights no longer stay on continuously when fuse 16 is removed and the IGN is on, correct?

If i replace 16 and pull one, the brake lights are out and the right turn signal stays on, does not flash but left works fine

What about the run-on condition I asked about… “truck will not shut off until i release the brake pedal”? Does it go away when either fuse is removed?