Overdrive wiring question

[Van Bagley]

Where does the overdrive get it's power?
There are 3 wires that come from the switch ( steering column) and they all go to the relay. 2 wires from the relay go to the OD itself plus a ground. The relay is new and I assume it works.
Van

 

[sunalp]

That depends on what car you have and whether it has the original harness or not.
I've only seen this on later cars ( Series 3-V) and can only speak to them, On the passenger
side of the engine bay where the wiring comes through the bulkhead there should be a white wire
with a connector on it. The O/D. The relay should be mounted over there as well and that white
wire is the switched power for the O/D.

If you gave an aftermarket harness any switched circuit will work.

Just to clarify, a switched circuit turns on & off with the ignition key.

Hope that helps,
Cheers!
Steve

 

[hartmandm]

The white wire Steve mentioned on my Series V:


OD wiring circuit for later self-canceling setups:



You mentioned your relay is new. Is it a modified relay from Alpine Innovations that provides the self-canceling behavior?

Mike

 

[pruyter]

In fact the connection from the column overdrive switch to the overdrive warning light goes via the lighting switch.
I know this because it has costed me a lot of time to figuere out why the battery was draining power and why the igniton warning light came on when the gear stick was parked in 3th or 4th gear while the igntion switch was OFF.
The culprit? Yes, the lighting switch which had an internal shortage with the consquense tha the relay was powered via the connection lighting switch, overdrive column switch to the relay.
Why had Rootes made this connection via the lighting switch? I guess because there is an resistor built in in the lighting switch which helps reduce the brightness of the warning light which can be helpful when driving in the dark.

Regards,

Peter

 

[hartmandm]

Peter,

Was your overdrive installed at the factory? I assume you have a series 4 or earlier. The diagram above is one I modified to add the OD Lamp, since the series 5 factory overdrive setup did not have the OD warning light. I did not involve any dash switches when wiring up my OD. Van Bagley is adding an OD to his series 5.

Mike

 

[pruyter]

Mike

Actually the car is a Rapier series IV. In WSM 124 is showed the wiring via the lighting switch. I haven't checked if the wiring for the Alpine series IV is different, I will check that tomorrow when I have time.
In order to overcome the shorting lighting switch the wire is now attached as showed in your diagram.

Regards,

Peter

 

[pruyter]

I have checked the wiring diagram in WSM 124 and both the Rapier Series IV and the Alpine Series IV have an overdrive warning light which is wired via the lighting switch. The diagram in WSM 124 is shown in Section E (Gearbox and Overdrive) on page 18 fig. 13A.

Peter

 

[Tim R]

I don't know if this helps but this is how we wire the overdrive.

Tim R

 

[Van Bagley]

Thanks, this is very helpful.
I have a SV that I installed the OD into about 5 years ago. It has worked well until recently.

 

[Van Bagley]

All of the wiring in the entire car is new from headlight to tail light including all the under dash.

 

[pruyter]

Here below in fig. 13A is shown how Rootes wired the overdrive warning lamp in both the Rapier Series IV and the Alpine Series IV.
The warning lamp is wired via the lighting switch in which it seems a resistor is built in which probably serves a dimmed light and that could be an advantage while driving in the dark.

Regards,

Peter

 

[Tom H]

Van, the problem is most likely electrical. Easy to test with just a test light.
1) pull powe lead off the coil while testing. with car in 1st gear and ignition On you should have no voltage at terminal C2
2) put car into 3 or 4 gear. You should have 12 v at C2. If not the 3/4 switch on the tranny is either bad or needs shims removed ( very common problem).
3) if step 2 shows 12v move OD lever into engage position and hold there. You should have 12 v at C4. If not switch is bad ( not likely)
4) release switch. C4 should still have 12 v . If not the relay is bad. Then test for 12 v at C1. If no 12 v at C1, relay is bad. (quite common)
5) if 12 v at c1 but you hear no clunk from the solenoid down at the tranny your solenoid is probably bad.
If you hear the relay click and the solenoid clunk but the OD does not engage on the road the problem is most likely mechanical / internal to the tranny. But in general I’d guess that electrical is the problem 90%of the time.

I assume your new wiring is not like original so color codes on wiring is not as in the manual.