cockpit brake lamp

[interested!]

Hi! I am having a problem with the cockpit brake ( red ) lamp , this is coming on while I am moving and braking . It goes out when moving off -handbrake released , but comes on almost every time I depress the footbrake pedal ,even lightly . The reservoir is topped up to max ,the reservoir switch works , comes on when free of the reservoir , goes out when fitted . Any ideas anyone ?. Only seems to come on when the engine is running and the brake pedal depressed -even at rest! the ABS lamp is NOT lighting up at the same time , , the pads are good , and braking in a straight line .

[Bill UK]

Sound`s like the lamp failure unit in the boot (trunk) its located under the rear lamp unit (drivers side for RHD Supra`s) the PCB normally suffers from corrosion, due water leakage from the hatch or lamp unit

[Bill UK]

The good and the bad.

[interested!]

Hi! Thanks for your reply ! , I did replace my old unit recently with a second-hand unit due to corrosion -as shown in your 2nd picture , and following your reply , I think this one is also playing up too! . The first time both the lamp failure lamp AND the red brake lamp came on , now only the brake lamp and even then only when I " touch " the footbrake pedal while moving . When I get it fixed I'll post a reply to this post with the solution .

[cre]

Have you checked to see how the fluid level is with the engine running and someone pressing the brake pedal?

[interested!]

Originally Posted by Bill UK

The good and the bad.

Hi! -- I've been away from my car for a while but now I have carried out a deep investigation and found that the problem was --a lamp failure unit
partially full of water , this was shorting out the lamp curcuit when braking , deeper investigation found that the lip under the rubber weather trim had rusted away in several places allowing water to enter the interior ,AND ,after opening the unit I found the curcuit board had corroded away --see picture above . I will now repair the lip and search for another unit , this one has been eaten away too! . The next unit I get , I will drill some drainage holes in the cover and then reassemble , purely as a secondary precaution.

[cre]

Hatch seal, rear wiper seal and tail lamp seal are the three entry points to be checked and repaired. Not only do these commonly kill the TLFM but they also usually cause some of the hardest rust to repair on this car.

I wouldn't drill more than one or two weeps in the bottom of the housing... I'd worry more about keeping the water out to begin with. Place it in a zip lock bag with the mount at the bottom of the bag, then put the screw through the bag in that one spot. Leave the mouth of the bag (which is at the bottom) open and run the harness in through there. Remove any harness hangers which hold the harness too high as this gives water something to run along and follow into the TLFM.

[Ranma]

Originally Posted by interested!

Hi! -- I've been away from my car for a while but now I have carried out a deep investigation and found that the problem was --a lamp failure unit
partially full of water , this was shorting out the lamp curcuit when braking , deeper investigation found that the lip under the rubber weather trim had rusted away in several places allowing water to enter the interior ,AND ,after opening the unit I found the curcuit board had corroded away --see picture above . I will now repair the lip and search for another unit , this one has been eaten away too! . The next unit I get , I will drill some drainage holes in the cover and then reassemble , purely as a secondary precaution.

Well remove and replace the faulty parts. Should be easy enough, go to Radio Shack for the parts. The board is fine, just repair it.

[interested!]

Originally Posted by Ranma

Well remove and replace the faulty parts. Should be easy enough, go to Radio Shack for the parts. The board is fine, just repair it.

Hi Ranma ,Thanks for your feedback , I did try that but unfortunately they did not have the EXACT replacements .The capacitors are : 25v 471J = 470pf ( x4 ) , J= +/- 5% , 473Z = 0.047 ( x 2 ) ( no suffix- presume farad? ) Z = + 80% /- 20% ,checked all this on Google , also , the single row integrated curcuit blocks part number MB4210 8804 M83 ( 8 legs ) do not show up anywhere . Can anyone shed some light on the capacitor voltage as the only replacements are 16v , 100v and higher .Thanks.I am not up to speed with electronic components so I would rather replace with like for like or replace with another unit .

[interested!]

Originally Posted by interested!

Hi Ranma ,Thanks for your feedback , I did try that but unfortunately they did not have the EXACT replacements .The capacitors are : 25v 471J = 470pf ( x4 ) , J= +/- 5% , 473Z = 0.047 ( x 2 ) ( no suffix- presume farad? ) Z = + 80% /- 20% ,checked all this on Google , also , the single row integrated curcuit blocks part number MB4210 8804 M83 ( 8 legs ) do not show up anywhere . Can anyone shed some light on the capacitor voltage as the only replacements are 16v , 100v and higher .Thanks.I am not up to speed with electronic components so I would rather replace with like for like or replace with another unit .

I have found a curcuit board repairer and I have had my board ( lamp fail unit part number 89373-14020 ) repaired by :

R and G Technology
Unit 10 Silverdale Industrial Estate
Worthing
West Sussex
BN11 2RZ

Tel 01903 202345 mailto:sales@randgtechnology.co.uk

I am very pleased with the results and I now have the unit refitted and working again . Below are the pictures of the board in after and before state .








I recommend this Company if you have any curcuit board problems .