Brake light issues after gearbox repairs

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

Hi

Been having some gearbox re-servicing done after encountering totally incompetent 'specialists' who stuffed the 2nd gear syncro for me.
Anyway the new experts repaired everything nicely but I now have an electrical issue where the handbrake light comes on for 1/2 second when changing up from 1st to 2nd or 2nd to 3rd. No other change produces the problem.

I've been under the truck and cleaned / re-seated all the plugs I can see but the problem persists.
I don't want to take the truck back top the gearbox guys as they are not electrical people and I can see the shit fight I'll be heading into.
If anyone has some useful solutions to what they might have screwed up, I'd like to deal with it myself and know its done right.

Any clues?

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Look inside around the console. The brake light is activated by a switch on the hand brake. Maybe a loose connection or a wire that has been pinched by the console when it was replaced.

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

nah, tried that. Currently running with the switch disconnected and still does it.
It appears that depressing the clutch pedal is what triggers the light - but only 1st to 2nd and 2nd to 3rd.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Trace the wiring then, it has to be something simple like a pinched wire. With the engine off do the gear changes without the clutch and see if it is the clutch or the gear lever. Then look near the culprit.

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

Trace the wiring then, it has to be something simple like a pinched wire. With the engine off do the gear changes without the clutch and see if it is the clutch or the gear lever. Then look near the culprit.

No pinched wire that I can see. There's bugger all of them.
Forgot to mention it only does it when the revs are around 1500 - 2000

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

No pinched wire that I can see. There's bugger all of them.
Forgot to mention it only does it when the revs are around 1500 - 2000

If it only happening when you press the clutch peddle, then check under the carpet where the clutch peddle levers against, you may find that you are crushing a wire loom that has shifted slightly, causing a short of that circuit. It may be a split insulation tube around the wires (not the conduit)

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

Thanks all.
I understand the concept of tracing out faulty circuits as I'm an electronics engineer. I guess what I'm after is any info relating to what the engine management computer might put out in response to screwed up wiring.
Whilst the idea of tracing fault is all well and good, this has only occurred since the gearbox was reinstalled. The mechanics have done something but I'm unable to track down what that something might be.
I was hoping someone else might have had the same problem.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Malcolm it is a really basic system with a switch on the parking brake lever and a cable running up to the dash. Looking at the loom layout on ToyoDIY the loom runs up the middle of the console and then across to the dash. I can't work out how the gear change or clutch or engine speed can affect it other than the cable has been pinched when the console has been replaced. If you remove the console does it still light up? If yes then lift the loom out of the clips and support it and try again. I cannot see it being anything other than the cable has been damaged and needs to be loved.

[Playdoh96 Member Find all posts View Profile Close Playdoh96]

This might sound silly but have you checked the brake fluid level. Just a thought

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

This might sound silly but have you checked the brake fluid level. Just a thought

Hmmmmmmmmmmmmmmm. Makes lots of sense.

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

yes I have.
some cars (Skylines) show the handbrake light when the fluid level goes down but mines nice and full.

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

yes I have.
some cars (Skylines) show the handbrake light when the fluid level goes down but mines nice and full.

[Playdoh96 Member Find all posts View Profile Close Playdoh96]

You might even have a faulty float in the reservoir. If you unplug the sensor should be enough just to test that side of the wiring.

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

Nope. checked that also.
Also if it was anything like that, it'd be happening in any gear on heavily corrugated dirt roads but it does not.
Its very predictable, put in 1st gear, get up to around 1500-2000 rpm, push in clutch, flash of brake light, move to 2nd gear, get to 1500-2000 rpm, push in clutch, flash of brake light, put in 2rd, no more flashes till back in 2nd or 1st. Its no worse or better on dirt.

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

Well if you went back to them you might have what you call a shit fight.
There's nothing I can think of that they could have done to cause this.
Maybe checking that wire near the handbrake as the would have had to remove console parts.

I think it might be coincidence, this does happen contrary to popular beliefs that who worked on the car last stuffed everything else that goes wrong for the next year ppl do stuff things a lot, so I understand this.
The brake light should only come on for the handbrake switch/wire or master cylinder switch/wire.

Very interesting that it does not do it sitting still, or with braking as it seems you are describing it coming on with the inertia of acceleration or deceleration.
I'd be fiddling around with the float at the master or by pass that to eliminate it as you have the handbrake.
Then that leaves you with a wiring problem maybe??????? Checking around the clutch pedal like said.

Please let us know what u find.