Alternator wiring harness - Lucas Alternator

Candellara · Post by **Candellara** » Sun Feb 15, 2015 9:02 am

Hi chaps

I'm going to replace the alternator and engine bay wiring harness on my 69 S2 4.2

I've received the AutoSparks looms - does anyone have a wiring diagram for the alternator loom as the old wiring has degraded and it's impossible to see the colours on the wires

Any help would be appresiated

iani · Post by **iani** » Sun Feb 15, 2015 9:35 am

According to the CAC wiring diagram:

Brown/Yellow - AL on Alternator to AL on 3AW warning unit

Brown/Purple - F+ on Alternator to C2 on Alternator Relay

Brown/Green - F- on Alternator to F on Regulator

Brown - B+ on Alternator to Earth (common with Starter motor)

Ian

Gfhug · Post by **Gfhug** » Sun Feb 15, 2015 9:39 am

https://dl.dropboxusercontent.com/u/849 ... Colour.jpg
Will this help from the knowledge section?

Candellara · Post by **Candellara** » Sun Feb 15, 2015 7:39 pm

Thanks Guys

Spent most of the day testing the continuity of all the existing wiring and slowly replacing the loom from the alternator backwards.

All going great - alternator connected up, relay connected, earth on N/S bulkhead, voltage regulator :-)

Brilliant until ............................

:x :x :x

The loom is wrong. The original has just three wires that connect inside the car (as does the replacement)

Original wiring:

One wire to the left hand side of the left fusebox (3rd fusebank) Brown - feeds to battery positive (shortest wire)
One wire to the right hand side of the right fusebox (3rd fusebank) White - feeds to relay (medium length)
One wire to the ignition switch (piggybacked onto another wire) - Brown - feeds to battery positive (longest)

On the new loom i have

Shortest length for left of left fusebox (Brown battery +) OK - but too short to reach
Medium length for right of right fusebox (Brown) - (should be white? and feeds to relay) - but too short to reach
Longest length for ignition switch (White) - too short and should be Brown and feeding to battery +

Arghhh!! Any idea's or anyone had this problem? Loom came from SNG

Gfhug · Post by **Gfhug** » Sun Feb 15, 2015 10:03 pm

Chat to SNG to get their feedback, maybe?
Can you make up temporary extensions to replicate what you had to see if that gives you a working circuit?

Sorry, wish I could help more. Good luck

abowie · Post by **abowie** » Mon Feb 16, 2015 4:10 am

Candellara wrote:
Arghhh!! Any idea's or anyone had this problem? Loom came from SNG

They're probably sent the wrong loom.

Post by **1954Etype** » Mon Feb 16, 2015 7:26 am

It could be that you have the routing wrong? Also, we have to extend one of the wires to the ignition switch when converting to RHD unless we move the ignition switch to the lhs of the column.

Candellara · Post by **Candellara** » Mon Feb 16, 2015 8:43 am

I'll have a chat with SNG this morning.

Everything is correct about the loom except the length of the three wires that connect internally.

The wire wire is too long and should fit to the RHS fusebox and the brown wire that wires to the ignition switch is too short

Either it's a manufacturing fault or i'll have to cut down the white wire and extend the ignition switch brown wire :?

Post by **mgcjag** » Mon Feb 16, 2015 9:00 am

Hi...did u not say in your previous post that the colours were also incorrect...Steve

Candellara · Post by **Candellara** » Mon Feb 16, 2015 9:26 am

mgcjag wrote:Hi...did u not say in your previous post that the colours were also incorrect...Steve

Yes & no. The original loom has two brown wires and one white.

The white wire - should be brown and a vice versa. Hope that makes sense

But - an update. I've spoken with AutoSparks and uncovered the mystery

My car has a 45amp Lucas alternator fitted and this was the loom that was ordered.

The Lucas 60Amp wiring harness is identical except - it differs in overall length and the three wires that run into the dash area are as per my original (the brown wire is the longest with a sleeving) rather than the white

So, the upshot seems to be - my car has a 45amp Lucas fitted - but the car was originally specified with a 60Amp Lucas unit and this is where the issue lays

I'll update when the new harness arrives :-)

Ropariva · Post by **Ropariva** » Wed Mar 04, 2015 5:17 am

Unfortunately I had the same problem
It was my own fault for placing an order for the 45 amp loom when I should have gotten the 60 amp loom.
I have to say though the AutoSparks website and their pre sales could have helped prevent the mix up.....long story
Anyway, there are a few differences in the looms as you have already worked out. You will find the connections at the alternator also vary. The main connection on the 45 amp loom has a lug to attach to a post. The 60 amp loom has a large spade connector. If you have the 45 amp alternator you may have to do a bit of modification at the terminal end.
The other difference is in the cable specification of the main brown alternator wire. The 60 amp loom uses 120/0.30 cable that is rated at 60 amps continuous and the 45 amp loom uses 84/0.30 that is rated at 42 amps continuous.
I ended up modifying my incorrect loom to fit. My only concern is the maximum charging current through the alternator cable, but as I'm unlikely to be fitting any high current headlights and doing extended night driving, I don't think my under rated loom will be a problem. All the best. Alan

Candellara · Post by **Candellara** » Wed Mar 04, 2015 2:56 pm

Interesting Alan. I got the loom re-supplied & fitted the correct 60amp version

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Alternator wiring harness - Lucas Alternator

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