Wiper Switch Repair on a TCS

[4129R]

I tried to get the wipers working after the car had not been used for very many years.

It turned out the switch was not working, and when shorting out the terminals the wipers thankfully worked perfectly.

I detached the wiper switch from the plate that mounts behind the steering wheel by drilling out two pop rivets, carefully opened the switch to exposed the drum terminals, soaked the copper drum terminals in vinegar for 5 hours moving the switch to a different position after 2 hours so all the terminals were exposed, washed the switch in clean water, dried it, and sprayed it with WD40, pop riveted it back together again aligning the drums carefully into the holes in the top plate and thankfully the switch now works perfectly. 

All my spare washer/wiper switches were for the wiper/washer switch on the left whereas this switch that I repaired had the wiper/washer on the right.

[Fotog]

Good job, man!  It can be very satisfying to fix even simple things, right?

Vince

[4129R]

Good job, man!  It can be very satisfying to fix even simple things, right?

Vince

I used to use vinegar to clean old coins very many years ago. The old British penny came up like new after soaking in vinegar, so I thought it would work on this switch. Since the switch did not work at all, I thought I had nothing to lose by trying to repair it. I expected the terminals to be corroded, but not as badly as they were.

It may be possible to clean the terminals without dismantling the switch, as the vinegar would probably get to all the corroded parts without pulling the switch apart. If it corroded, it would be exposed to air and moisture, so the vinegar could get to those parts and reverse the corrosion.

I had the same corrosion problem on the terminal part of the ignition switch. I pulled it apart, cleaned it, put it back together again, it worked for a short while and then fell apart. Luckily Rimmer Bros, Triumph specialists, had the right part, and the rubber shroud it comes with holds the terminal block to the key part very well.

Tracing many electrical faults, I have found that the faults are caused by either 1) corrosion in the motor or bulb holder, 2) faulty bulbs, 3) faulty earth, or 4) surprisingly, when putting in new wiring looms, there are parts where there is no earth at all, so I have had to run separate earth wires. The window motor earth wire only connects to the door interior light earth switch and the metal bracket holding the door switch and the ends of the dashboard. So that earth does not link to the chassis. I had to run a wire from the metal dash end bracket to the metal dash central bracket which is bolted to the chassis just north of the gear lever.

You have to be in the right mood to trace electrical faults. I have had 12v showing at the electrical part, (right side headlight) and it still not working. I changed the blue/red wire for another, and it worked perfectly. I cannot explain why the first wire did not get the bulb working with 12v showing, but a simple wire change got it to work.

I have no idea how the horn earths through the steering column switch. It seems to be connected to a main beam wire. Another mystery.

When tracing faults on the indicators, unless the correct wattage bulbs are all connected and working, the indicators will not flash. They need the proper load to make the bi-metallic strip heat up and go off or they just stay permanently on with too low a load.

[jbcollier]

"I have had 12v showing at the electrical part, (right side headlight) and it still not working. I changed the blue/red wire for another, and it worked perfectly. I cannot explain why the first wire did not get the bulb working with 12v showing, but a simple wire change got it to work."

If you are using a "no-load" system to check for voltage, then it is easy to get false positives.  Digital multimeters will "smell" full voltage through corroded connections and mostly broken wires.  If you use a test light with an incandescent bulb, this applies a load to the circuit and the intensity of the light will give a much better indication of the voltage available.

"I have no idea how the horn earths through the steering column switch."

Early cars:

PB is the ground wire from the horn.  It goes up the steering column to the horn ring.  The horn ring connects to the horn button via the horn brush.  The horn button has a ground tab on one side that touches the steering wheel hub.  The ground path goes through the hub to the column.  The column goes to the steering rack via a ground strap on the steering column u-joint.  The steering rack is attached/grounded to the chassis.

Later/last cars:

The horn does not ground through the column.  Rather than controlling the ground, the switch controls the power by connecting P to PB.

Using acid to clean connections is fine but make sure you treat the newly cleaned terminals/connections with an antioxidant afterwards.  I use dielectric grease as it also providing lubricant for moving contacts.

[4129R]

"I have had 12v showing at the electrical part, (right side headlight) and it still not working. I changed the blue/red wire for another, and it worked perfectly. I cannot explain why the first wire did not get the bulb working with 12v showing, but a simple wire change got it to work."

If you are using a "no-load" system to check for voltage, then it is easy to get false positives.  Digital multimeters will "smell" full voltage through corroded connections and mostly broken wires.  If you use a test light with an incandescent bulb, this applies a load to the circuit and the intensity of the light will give a much better indication of the voltage available.

"I have no idea how the horn earths through the steering column switch."

Early cars:

PB is the ground wire from the horn.  It goes up the steering column to the horn ring.  The horn ring connects to the horn button via the horn brush.  The horn button has a ground tab on one side that touches the steering wheel hub.  The ground path goes through the hub to the column.  The column goes to the steering rack via a ground strap on the steering column u-joint.  The steering rack is attached/grounded to the chassis.

Later/last cars:

The horn does not ground through the column.  Rather than controlling the ground, the switch controls the power by connecting P to PB.

Using acid to clean connections is fine but make sure you treat the newly cleaned terminals/connections with an antioxidant afterwards.  I use dielectric grease as it also providing lubricant for moving contacts.

Thank you for the explanation.

All seems working now, time to fire the engine up and get 4259R moving under its own power for about 30 years.