Alternator wiring

[Candellara]

Hi Chaps,

Thought i'd tap into your fountain of knowledge.

Refurbing an ex-racer is proving to have it's ups and downs. Firstly, the front brake fluid reservoir wiring had been disconnected (i assume you wouldn't want warning lights flashing on when your're running around the track unless oil or temps)

Anyhow, i replaced all the reservoirs and reconnected the front reservoir wiring - hey presto all good and working :-)

I couldn't "find" the wiring for the rear reservoir brake fluid warning initially - however after un-taping the loom on the N/S frame it appears that it had been disconnected and the earth part of this loom been connected to part of the alternator wiring :-( with the positive wire for the brake fluid reservoir just wrapped into the loom

Obviously, i am keen to re-instate this rear reservoir warning lamp and if i unplug these two wires and connect to the reservoir - the brake fluid warning lamp works correctly.

So, i now have a situation whereby there are four wires off the alternator:

Main thick battery + - connected and ok
Earth - connected to the alternator body - connected ok
F+ - this was connected to the brake reservoir loom - earth
A N other wire - goes into the main loom

I suppose my question would be - where should the F+ and A N Other wire route to?

[christopher storey]

They should route to the multiplug connector to the 4TR alternator control unit which lies under the heater box on the left side of the firewall

[Candellara]

Many thanks Chris

I will have a look this evening

Jason

[Candellara]

Hmmm, lots of head scratching going on now.

B+ lead from alternator - correct
AL lead - runs from alternator to 3AW charging lamp relay - correct
F- lead - runs from alternator to Voltage Reg - correct
F+ lead - should run to switched supply from relay in the wheel arch.
The relay switches ok but if the F+ lead is connected to this the alternator warning lamp stays on and no charge present

If you connect the F+ lead to earth - alternator lamp goes out and charges correctly???

Something not right as the F+ lead should "energise" the alternator?

Voltage reg, relay and 3AW relay all appear to work ok. Faulty alternator?

Any hints or tips chaps as both the auto electrician and i are scratching our heads

[christopher storey]

have you any colours on the wires ? The + terminal on the 4TR should have a brown and purple wire to it. The - terminal on the 4TR should have a black wire to it. The Field wire should be Brown and green .

[Candellara]

The wires are obviously very dirty Chris, but everything seems to be connected correctly however - something in the past has failed (i think)

The F+ wire (Brown/Purple)(connected to the 4TR and the alternator relay) should provide ign live to the F+ terminal (Brown/Purple) on the alternator. When this is connected (as per wiring diagrams) the ignition light remains on and no charge from the alternator.

Everything checks out in terms of all the wiring is correct however if we disconnect the brown/purple wire from the 6RA to the alternator F+ and when the F+ terminal on the alternator is just grounded to earth, the ignition lamp goes out and the battery charges correctly. This was only uncovered when i was tracing the connections for the rear brake fluid warning light and found that the - wire was connected to a wire running from the F+ terminal rather than the F+ terminal being wired correctly to the 6RA relay

My auto-electrician is scratching his head and thinks that we need to get the 4TR and alternator bench tested by a specialist

[Candellara]

Quick update on this thread.

Sent the alternator & voltage reg to a specialist alternator company for bench testing - no fault found!

So, armed with another alternator and regulator, my auto electrician set up his own bench test to try & replicate the fault.

Hey presto - alternator fine but faulty regulator. We'll re-install the alternator with a new regulator and we've put another issue to bed :-)

[Candellara]

All done. Alternator re-installed, new 4TR regulator and all wiring reconnected as it was originally installed. Everything working correctly