I have a 1989 XJS here in the UK and none of the brake lights are working. I do not have a third top brake light on my car.

I have checked the 10amp fuse under the dash, which is fine, but have not been able to locate a relay for the brake lights. I am assuming it is a bad brake pedal switch, but I wanted to locate the relay first before purchasing a new switch. Any guidance on where I should look? I tried searching this forum, but did not find a definitive answer. Thanks in advance.

P.S. I don't know how this could be related, but lately, whenever I press the brake pedal for the first few times, it sounds like a pump starts working on the passenger side. It comes on for a few seconds, kinda groaning, and then stops. Is this normal, or a sign that I need a new abs pump?

 

Do you have voltage on both sides of the brake light switch when the pedal is depressed??


You'll have to wait on someone with more ABS knowledge but from some pictures I have seen, the accumulator and pump are on the opposite side of the master cylinder on some cars. It should not be making a noticeable noise so I would check the brake fluid level and condition and verify the accumulator is okay. Press the pedal after the car is shut off, you should have about 2 full power assisted braking operations and then it will get more difficult.

 

I'm a newb at electrical stuff. How would I figure out whether I have voltage on both sides of the switch? I'm sure it involves a multimeter; I'm just asking where I should place the leads. Thanks.

 

Check the relay first its under the bonnet on the RH side inner fender. I have had mine come loose before.

 

The ABS pump usually makes a noise as it kicks in to resupply pressure on start up; if it runs all the time then there is a problem somewhere.

 

The simplest way is to buy a circuit tester screwdriver. This is a small screwdriver-like object with a wire coming out of it with a crocodile clip on the end of the wire, and a light set into the handle of the screwdriver. Clip the clip onto an earth (ie a bit of bare metal; eg the column fixing bolts etc etc) and touch the end of the screwdriver to the cable or connector you want to test for current. If the light comes on there is current.

For the brake light circuit the ignition must be in the first position, at least, if not ignition on. For an example of a test light see:

HEAVY DUTY 6-12V AUTOMOTIVE ELECTRICAL CIRCUIT TESTER | eBay
or

There are also meters for this purpose, but they are a bit more complicated to use.

Basically, current comes out of the battery via the positive terminal though insulated wires to the device that needs power. After the device, the current is returned (ie the circuit completed back to the battery) merely by feeding it to a convenient earthing place near the device concerned. The current then makes its way through the metal of the body back to the battery via the large earthing bolt terminal in the boot that the large negative battery terminal it is connected to. In testing a circuit, you are trying to ascertain why this circuit is not functioning (ie where the break in the circuit is). So it could be the fuse, it could be the switch on the pedal, it could be a fractured wire somewhere, etc etc. The tester by helping you find out where the current in the circuit is reaching to, helps to find the break and thus the cause of the trouble.

Greg

 

This is the ABS pump and it should run when the car is first started and will run sometimes during normal operation as it keeps pressure in the braking system up, Sounds normal to me.

 

Wow, guys. I really appreciate your help! I will check the relay. Since I have no idea when the last owner changed his brake fluid I will get that done soon. Perhaps that will make a difference to the frequency of the he pump activation, which seems to be increasing.

 

Just an update. The brake lights are now working. It turned out to be a faulty brakelight switch. Replaced, after much struggling in the confined space under the dash, with PART NO. DBC2960. (valid up to VIN 179736): Part no. DBC2960 | Brake pedal microswitch parts from Jaguar Classic Parts UK

One question: The part that I got had an extra connector for the speed control system (that black cylinder connector in the diagram). I don't have anything to connect that to, so I just left it dangling.

Did all 1989 3.6 models in the UK have speed control? I have a speed control button on the center console, but do not have a speed control switch on the turn signal stalk.

Thanks again for the help!

 

I am confused, and perhaps second guessing myself because you have a RHD 3.6...

What I want to say is that no XJS really had options. If by speed control you mean cruise control, they all have it and the controls are on the center console, there is no stalk control for it.

all the stalks do is control high beams, turn signals, wipers and washers

 

Not necessarily; my (V12) has cruise and there is a 'resume' button on the end of the indicator stalk.

 

Quite correct. On UK V12s there were times when CC was an option and times when it came as standard in the 1980s. On 3.6 models it was (I believe) always an option. As Steve says, if CC was fitted to PRE- semi facelifted cars (ie pre about 1987/8 models that did not have the Ford switchgear on the column and did not have the narrower Recara style seats) the indicator stalk had a resume button on the end. If it did not have CC the stalk did not have it.

It is possible that on Hamiltonian's car the blanking piece on the right hand side of the skislope that went in the hole where the CC switch would go if there was such fitted, was lost and a previous owner put a CC switch in there just to fill the hole. IF his car HAS got CC, then carefully prising out this switch and seeing if there are any wires attached should determine the matter.

As for getting it to work, that would be another matter!

Greg

 

Thanks for the information. I have a feeling some significant work had been done on the controls and dash area at some point, so the stalk control with "resume" could have been replaced at some point. I won't bother to check this out until I need to take the ski-jump area apart (a future project to fix a bad ground from the stereo, which is getting buzzing interference from the alternator).

There was not a lot of history with my car, other than the previous owner purchased it in 2007 for 500 pounds, and set to work restoring it to a decent level -- although, as I'm finding out, he left some major work undone (mostly with the suspension).

 

ohhh yeahhh....sorry, I forgot that resume part was on the stalk because I never use my cruise since I haven't ever fixed it.

The switch on the center console changed around a little from year to year and I believe the column stalks are compatible across the XJ platoform as well, so it is very possible the turn indicator switch didn't work and he picked up the incorrect spare somewhere. Which obviously still fit just fine

 

The brake lights will not shut off when the brake pedal is off
removed the BP Switch found that the micro sw was not working properly// oddly enough the power to the lights are on when not pressing on the pedal // i have continuity when not pressing on the brake pedal
whats that all about is their a FAIL SAFE in line somewhere ?
I ordered a new sw

 

I have never seen a vehicle where the electrical scheme was set to turn the brake lights on automatically if some part of the circuit failed. You either have a short somewhere or you are mistaking running lights for brake lights. Is your third brake light on?

 

If the brake lights are on without the oedal being pressed, there's a short or a failure in the brake light switch or light circuit. The default is not to be on.

Good luck

Paul