Losing 2v somewhere - Ignition Switch?

[JohnFol]

Afternoon all, I get ~9-10v on rear lights / wiper motor when earthing via a lead directly connected to battery -ve (so that rules out a poor earth). I get 14.1v from alternator so suspect the supply side.

I'm gradually going through the electrics and have replaced battery, replaced main wiring to starter motor / alternator / fuse box, replaced HT leads, replaced coil, refurbished starter and alternator, starter now fired by relay etc. and happy to replace / renew parts as I go along.

Other symptom is firing engine is sometimes sluggish, but sparks up really well when it turns.

I have a week off soon, so want to line up parts. Does this sound like a failing ignition switch?

[peteracs]

Hi John

To confirm it is the light switch etc, I suggest take off the steering cowling and measure the input and output voltages from the switches.

For the lights I have relays for the side/low and high beams and on Eric’s suggestion will be looking to do the same on the wiper motor.

This removes the loading from the switch assembly on the steering wheel.

Peter

[JohnFol]

12.1 in, 10.3 out on Green / black and similar for starter cable...

Looks like the electrical part of the mechanism is non serviceable

[JohnFol]

Just a FYI I found a replacement (new) ignition switch, and have details if anyone is interested

[LanciaDave]

I am interested

[Nigel]

John, old topic, but did you find where your voltage drop was?

I have similar drops [10.4] on 2 fuses #11 and #12, the latter
for wipers and indicators.
I also fitted a new ignition switch but this didn't solve my problem.

Nigel

[JohnFol]

Nigel, apologies for not seeing this but I have a bit of time to diagnose.

I've had new ignition switch in for a while and still about 9v at rear lights, and on first few fuses.

I've also replaced the battery to fuse box cables (one each side of fuse box).

Has anyone else found a solution before I start tracking the voltage through the car?

[Nigel]

John,
Your issues mirror mine in many ways.
As you know earthing points are a go-to first look, I had checked all mine and
still had low voltage.
The loom is plagued with multiple connectors on the live side. One is the
16/20 way block in the pax footwell. The rear looms also have connectors each side.

I also found that wires, although appearing sound, corrode within. Stripping back a wire
to redo a connector often finds a copper core that's gone black. This condition is un-solderable
and fails to make a good joint even when crimped.

My issues were wipers and indicators. I ended up completely rewiring these 2 circuits, and the result
was excellent. I expect to have to do a lot more in the future.

Hope this helps in a small way.
Nigel

[JohnFol]

Thanks Nigel.
I invested in a power probe and I can apply 12 or earth directly from the battery to anywhere via the tip.

Managed to confirm rear earth is ok, and "injecting" 12v solved the issue.

I found the rear connection you mentioned and that accounts for nearly 1v so tracing the loom back is on the list.