Hello All,

I urgently need to locate the bulb check unit on my 1990 XJS convertible (RHD). I found a post describing it as the second component from the top left in the main fuse panel, but when looking at the panel underneath the passenger-side dash, I only see two relays and a few fuses. Could somebody please tell me where this unit is, and what it looks like?

My handbrake indicator light doesn't work, but the switch is working, since the convertible top won't lower until I engage the handbrake. I'm hoping that disconnecting the bulb check unit will cause this to work, so my car will pass inspection. If anyone has any ideas, I'm all ears!

Best regards to All

 

There are several bulb check units.

The one for the brake lights is in the center console and, at a glance, looks like a relay

For front running lights the two BFUs are on the RH component panel. For the rears, they're in the trunk, left and right sides





Cheers
DD

 

Just to clarify, the handbrake warning light isn't linked to any of the bulb failure units, which only cover sidelights/ taillights and rear brake lights and numberplate lights.

Good luck

Paul

 

Hi Paul,

The bulb check unit is different from the bulb failure units. I've attached the page describing it from Publication S-57/90, Electrical Guide XJ-S 1990/1991 MY. As you can see from the schematic, the bulb check unit is directly connected to the handbrake warning light. This is the unit I'm trying to locate.

Thanks,

Dino



Bulb check unit

 

Ahhhh. My apologies. I was confused. Lack of coffee is my excuse. Plus, the sun was in my eyes :-)

I can't remember where where the check unit is, if I ever knew

Cheers
DD

 

If the bulb check unit is the one that also does the brakelights, then on coupés itis located under the central console armrest cubby box. On my car it can be accessed by removing the cubby box lining.

 

Yes, it also does the brake lights. I'll have a look under the console, thank you!

 

The Bulb Check Unit shown in post #4 above is intended to turn the warning lights on ("check" them) when you start the car.

The device under the console cubby box is the Brake Light Failure Unit.

Both are tied-in with the parking brake warning lamp

Cheers
DD

 

Well, I've just confirmed that the Bulb Check Unit is definitely not underneath the console cubby box. I have the factory manuals, and I cannot find any other reference to this unit, nor a hint to its location...rather stumped.

 

Under dash on left front component panel, apparently...

 

Thank you..I will take another look tomorrow. On the nearside (passenger) panel, there were only two relays, one of which is the ABS relay. Perhaps it's on the other side.

 

Solved! Thank you all for the helpful comments. Here are the details for any interested parties:

The Bulb Check Unit is a black, five-pin relay-looking thing manufactured by Pektron. It's plugged into a white connector, which is third from the left when you are looking up under the dash (great fun!) My bulb check unit is defective, and was causing the handbrake indicator to never illuminate. I've removed the bulb check unit and the handbrake indicator now functions correctly. If I can't find a replacement unit, I'll have a go at repairing the defective one, as the circuit is dead-simple according to the wiring diagram.

P.S.--I took the opportunity to put in LED replacements for the indicator bulbs. This is a great and inexpensive improvement!