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WB four speed reverse wire conversion
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Hi All,
I am changing out the three speed and fitting a M20 four speed in my WB 6cyl van. The reverse switch on the Three speed box is a single pin but the Four speed is a two pin. I just had a quick look at the wiring diagram in the Holden Manual but It just shows that there is a light green power wire running down to the backup lamps and then an earth wire leaving the lamps which is what I am assuming is the single wire going to the switch. Am I to intercept the light green wire running to the reverse lamp and run it through the switch so power is interrupted to the lamp when the car is not on reverse and if so what is earthing the bulb?? Am I then suppose to make sure the bulb is also earthed. Or do I just intercept the single earth wire that went to the three speed switch making it fit a two pin switch interrupting the earth when it is not in reverse?? Why the two different switches?? Am I going about this the hard way or do I have it all wrong. Cheers MS
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There should be a plug up under the dash with two wires: a dark green and light green wire (or could be pink and light green). Get yourself a factory 4spd wiring harness (two wires, light and dark green), runs from this plug, through a hole near to the shifter (LH side of it) under the mat/carpet and through to the reverse switch on the box.
This is how HQ-HZ are anyway. Not certain that WB are the same, but reverse lights is one area they do differ.
What diff ratio are you running? You may find if its too tall you'll hate the 4spd in reverse! |
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The single wire going to the switch on the 3-sp is the top gear switch for the anti-pollution solenoid valve, it has nothing to do with reverse gear. The 4-sp box also had this from 7/76 onwards.
As HK1837 has said, the 3-sp reverse switch is under the dash on the lower part of the steering column.
Dr Terry |
If at first you don't succeed, just call it Version 1.0 |
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quote:
Originally posted by Dr Terry
The single wire going to the switch on the 3-sp is the top gear switch for the anti-pollution solenoid valve, it has nothing to do with reverse gear. The 4-sp box also had this from 7/76 onwards.
As HK1837 has said, the 3-sp reverse switch is under the dash on the lower part of the steering column.
Dr Terry
Thanks for the replies. My box is from VH Commodore but does not appear to have any other switch's only the reverse switch so where should I attach the single wire that was on what I originally thought was the reverse switch as the engine bay is still all original with all the anti pollution gear still there?? Cheers MS
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Not an original VH box (or side cover), it will be from a pre ADR27A car, possibly the side cover is off a 3spd or 4spd. Just ground the wire, get a short piece of wire with a spade crimp-lug on one end and a ring crimp-lug on the other, plug it into the end of the existing wire and stick it under a bolt on the box.
If you want it to work as per original, swap the side cover over off the 3spd onto the 4spd. Leave the 3spd's 2nd/3rd selector fork as well as it has the flat spot on it to make the switch work (and the seal arrangement is different), but swap the 1st/2nd one over off the 4spd and remove the 1st/rev fork from the 3spd side cover. Use the 4spd's selector arms on the side of the box. You do the changeover with the box in neutral. |
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Hey HK1837,
Thanks again for all the information it is so much appreciated. The four speed box I have is in very good condition inside so I would say at some stage of the VH's life it was exchanged with the VH being fitted with the earlier box, but here I go again with another question, what anti pollution valve will I be earthing out constantly if I just run the wire to a bolt on the box? Cheers MS
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The solenoid on the driver's side of the engine that controls vacuum advance. The top gear switch (3rd in 3spd and trimatic, 4th in 4spd) runs in series with a little block temperature switch near to the dizzy. When both of these are happy (ie top gear and warm engine) it allows the engine to get full vacuum advance. The solenoid switches between vacuum sources. |
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To add to HK1837's comment, the solenoid is mounted on the thermostat housing at the front of the motor.
Dr Terry |
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Thank you Dr Terry and HK1837 for all of the information, it has been very useful and very much appreciated.
The vacuum line on the dizzy on my engine has been removed and the hose plugged I am assuming this was due to pinging brought on by the changes to unleaded petrol so I will probably just earth the wire out unless either of you think that it is worth fitting the side cover from the three speed box to accommodate the switch and then reattach the vacuum hose to the dizzy advance or do you think this will only cause pinging making the change over not worth while Cheers MS
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The only reason you might want it all there is in case of rego issues with having pollution equipment disconnected. You will want the vacuum advance fitted though, helps with fuel economy whilst cruising. A blue 202 shouldn't ping with 95 or 98 or even quality E10, they are pretty low compression engines. May just have a carbon buildup. This book has pretty good detail on the pollution equioment, how it is connected, what it is all for and how it works. You'll pick them up on Ebay or at swapmeets for $20 or less, or new for about $55-$60. http://www.ebay.com.au/i...ks_2&hash=item3a7cd6fa1f |
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WB four speed reverse wire conversion
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