Hi,

I've checked the bulbs / connections at the rear light cluster but it appears the problem is further back, as neither lights come on upon pressing the brake pedal, and there is no voltage registering at the bulb holder.

I guess it could be a corroded connection somewhere under the bus or a problem with the switch on the brake pedal? However I can't find any information in the walkers manual about where this switch is.

Can anybody help or provide a few tips as to what I should look at first?

Thanks,

David

My bus number (if any): RM1380

If you have the original type switch I think it is housed in an enclosure near the footbrake valve linked by a spring, however if you have a microswitch replacement I seem to remember accessing it by removing the radiator grill cover.

My brake lights packed up during an MOT on RM1797, it was a corroded terminal on the dip switch, Take off front grill to access, I replaced the switch, all sorted.
They can be bought for under £10.00 on ebay

Regards

Rob

My bus number (if any): RML2355

There's a terminal block under the stairs accessed through a panel about 4" sqare. Maybe corroded wires in there.

Hi,

Got to the bottom of this eventually. Just writing it up for future benifit of somebody hopefully...

To recap I was getting no brake lights, and so no 24V at the brake lights when pushing the brake pedal. (The bulbs were in when I was taking these readings).

Located brake foot switch which is directly underneath the pedal, shielded by a metal cover. Tried spraying WD40 into the switch to see if it helped but no difference.

Took off radiator cover (ok, I did this first) and found the wires from the switch under the brake pedal. These wires are on the offside side of the cover. Found that the switch is switching positive (not negative)... i.e. it is attached to a permenant 24V feed and the switch determines whether 24V +ve is passed backwards down the bus to the lights. Tested switch by cutting wires at the join and attaching multimeter. Switch was working fine.

Then found that the +ve output from the switch goes back to a junction box (well, a 'chocolate box' style connection strip that had rusted badly). This is above the luggage compartment (next to platform) accessed via a little inspection hole located in the slanted panel above luggage compartment... towards back of bus. You can actually see through this little hole to the rear light clusters.

Disconnected the brake light feed at the junction box. You can tell which one as the colours match up with the colours visible in the light clusters. At the light cluser itself you can see that neutral is shared by all the bulbs, so you know which one is the +ve supply for each bulb as the terminal is not shared with other bulbs and only has one wire going to it. Also could see that one wire (feed from the switch) was joined to two (one for each brake light) wires at the chocolate / juction box. Tested the +ve feed wire from the switch (tested where it splits at the junction box - but not connected to the lights at this point). It was reading 24V when pedal depressed so thought it was probably a bad connection at the junction box. Remade this join with a new junction box, but weirdly was still getting 0V at the brake lamp. It appeared that putting the bulb in the circuit caused 24V (when pedal pressed) to drop to 0V!

Conclusion was that though there was a connection, the voltage supply was so poor that the load of the lamp when inserted into the circuit meant that the voltage would drop to 0V as there was not enough current to drive the lamp - at least this is what I understand with my rusty GCSE knowledge of DC electrics!

In the cab to right of drivers seat, inside the big metal box are large terminals directly from the battery. This appears a good place to get a known good live or neutral feed from. I disconnected the only live feed going to the foot switch and replaced it with a new live feed directly from the +ve terminal. The wire can leave this box and run around the cab, through a wiring hole in the front bulkhead in front of your feet, and easily reach the switch wiring. Connect using crimped ring and spade terminals (though if you want to do properly there are some fully sealed waterproof versions that would be better as this area will probably get spray & rain passing through radiator).

Problem solved! However, if it hadn't worked then it would have been easy enough simply to run a new wire from the switch output to the junction box at the back of the bus - and this would have eliminated virtually all of the old duff wiring.

Thanks for everyone who helped with suggestions.

David

My bus number (if any): RM1380

Well done, the access hatch is the one I mentioned in my post. The problem you now have is a fire hazerd!!

It is not wise to permanently connect 24v to anything without going through a fuse; you get a short circuit, the wiring catches fire.

Get one of those blade type fues and put that between the battery + and the new wire you installed.

Most switching on RMs is + except gearbox EP coils which are switched -. Hence with any - to body, you get gearbox problems eventually. The gear selector is howver switching + , the change being done in the gear control panel!

It's never wise to test a circuit with a bulb left in as that provides resistance back to - and you get a false reading.