1800: Brake warning light

[VolvoFan]

I have just bled the brakes on my 1972 1800E and everything works fine except the brake warning light does not light when the hand-brake is on.

For bleeding, I followed the Volvo w/s manual and removed the warning lamp switch near the master cylinder and refitted it afterwards.

I also ascertained that the warning light bulb was working by earthing the feed wire from the switch.

I haven't done any work on the hand-brake, so I can rule that out.

Any useful hints and tips would be appreciated, thanks.

[Volvo_133]

My late amazon has this set up. From memory there is a switch on the handbrake which completes the circuit to earth just the same as the brake system balance switch. Do the same test at the HB switch to decide a wiring or switch issue. I am asuming your car shares the same method.
Chris

[Ron Kwas]

VF;

I'm with Chris on this...check for the Handbrake Sensing Switch (under Handbrake Lever Gaiter), remove this wire wire from switch and connect to chassis (Ign ON). This should complete circuit similar to when you checked function at Differential Sensor. HSS doesn't get a lot of exercise, so may need to be cycled a bit, and need a drop of Deoxit D5, or even light oil to bring it back to normal function...

Ref: https://www.sw-em.com/Deoxit_D5_Additional.htm

Good Hunting

[VolvoFan]

Thank you both for your suggestions. However, since the warning light was working before bleeding the brakes and not afterwards, and not having done anything to the handbrake, I can't see why the handbrake warning switch could be faulty, unless it is purely a coincidence.

Nevertheless, I will investigate the handbrake switch, just in case!

Thanks again.

[Ron Kwas]

VF;

I would agree that seems odd...and I have no explanation for it other than the bulb might have coincidentally have burned out, or the sensing switch at Handbrake coincidentally went sluggish, or an associated electrical connection might have been mechanically disturbed during the bleeding operation and have gone open...all might/should be answered depending on what you find when troubleshooting...I'd start by first checking the Indicator again, by earthing sensing wire at Brake Diff Sensor (Ign ON!).

Good Hunting!

[powen1]

Hi, Cant see why your getting No light !- But I do know after bleeding sometimes you need to reset the Brake waning sensor near the master cylinder a black wire going to a Brake pipe junction if the brakes are unbalanced which may have been caused by bleeding - solution is to unscrew sensor fully and rescue back in, but as I say, normal fault is brake light stays on! not off Regards

[VolvoFan]

Problem solved. You were correct, Ron, in that the handbrake sensing switch had "gone sluggish": a clean up and WD40 application solved the problem. What a coincidence, and I was beginning to doubt my ability with the refitting of the pressure differential warning actuator.

I like it when jobs are simple to put right and free of charge!

Thanks again.

[Ron Kwas]

VF;

...happy to hear you had "an easy one", but beware, WD rhymes with whale pee (and that is coincidentally how I feel about it!)...it is mostly solvent and leaves little behind long-term...you wouldn't want to have symptoms return in a month would you?...a drop of Deoxit contact treatment or even Tri-Flow light oil would keep mechanism lubricated, and contacts protected for infinitely longer!

Cheers

[cassell]

Originally Posted by VolvoFan

Problem solved. You were correct, Ron, in that the handbrake sensing switch had "gone sluggish": a clean up and WD40 application solved the problem. What a coincidence, and I was beginning to doubt my ability with the refitting of the pressure differential warning actuator.

I like it when jobs are simple to put right and free of charge!

Thanks again.

I had excatly the same fault with my ES a while ago, unfortunately my switch was completely worn out/seized/kaput!

A quick call to Brookhouse Volvo, in stock, arrived by post the next day, and the best bit...just £13!

So if yours gives problems again, it's not a big deal.

[25PSi]

Originally Posted by Ron Kwas

VF;

...happy to hear you had "an easy one", but beware, WD rhymes with whale pee (and that is coincidentally how I feel about it!)...it is mostly solvent and leaves little behind long-term...you wouldn't want to have symptoms return in a month would you?...a drop of Deoxit contact treatment or even Tri-Flow light oil would keep mechanism lubricated, and contacts protected for infinitely longer!

Cheers

So, after hours of testing and probing and pocking i decipher it to be a bad connection from the tiny bulb to the holder itself. If i push slightly from one side light surely comes on as it should but on its own it just does not light up.

How can i address this with minimal "Blood"?