overdrive problems

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retro baz · #1 Post by **retro baz** » Sat Mar 27, 2004 5:10 pm

when driving home from the workshop 2day i noticed the overdrive was not working. 
where can i find the wires concerned with this and what other things can i check? 
i changed my points up the workshop and im not sure if i knocked something or pulled something. 
please help. 
cheers 
1500hl if that helps

Richard the old one · #2 Post by **Richard the old one** » Sun Mar 28, 2004 9:18 pm

I am assuming that you have checked your gearbox oil level. 
 
If so I recommend that you look for something simple first such as a problem with the electrics. 
 
If you get the car up on some ramps you should be able to find the solenoid coil that is fitted to the overdrive unit. You can identify it by the two wires that should be connected to it. One is a short black wire and it just goes from the solenoid to the body of the overdrive unit so providing the return path. The second one comes from the O/D switch on the gear stick. I have had problems in the past with these onnections dropping off. The other wire from the O/D switch provides the 12 volts that operates the solenoid when O/D is selected by operating the switch on the top of the gear stick and only when 3 or 4 gear is selected. Next check that you are getting 12v at this solenoid connection when the ignition is switched on and the conditions specific above are met. This can be done either with a multimeter or just a bulb with a suitable leads. I also think that I have read that the solenoid will heat up slightly under these conditions and this can be felt so confirming that the circuit is being made but I have not tried this out. 
 
If you do not get the voltage you need to check back through the circuit. I would go first for the switch on the gear stick as this is fairly easy to get at. I believe the connections to the switch can drop off due to vibration but I have not had that problem. I have had the switch fail which is not surprising as it gets a lot of use. If there is no volts present at this switch you need to check the 3/4 interlock switch which is situated on the top of the gearbox. If the voltage is getting to this switch but the switch is not making you need to see if there are any spacer washers under the switch a you may get it to make if you remove one or all of these washers if the problem is just a bit of wear on the ball end of the switch. 
 
All the best 
 
Richard the old one

retro baz · #3 Post by **retro baz** » Sun Mar 28, 2004 9:32 pm

cheers for the advise. 
i have checked all connections in the engine bay and they seem fine. 
i also took the gear stick out and checked them and there ok too. 
i haven't checked the oil yet but when you mentioned it i have noticed dome noise in the last couple of days leading up to it. 
i will give that a go after work. 
cheers again. 
Marc

Richard the old one · #4 Post by **Richard the old one** » Sun Mar 28, 2004 9:37 pm

You state that the connections look fine. Thats good but you need to check that switches are operating. Have you check that you are getting 12 volts to the solenoid coil ? 
 
Regards 
 
Richard the old one

retro baz · #5 Post by **retro baz** » Sun Mar 28, 2004 9:59 pm

not yet. i will bring my multimeter home from work 2morro and give it a bash. 
i have only been without it a day but i miss it already. 
i didn't think i used it that much. 
when i was reading the manual it was saying do not under any circumstance reverse in overdrive. 
why is this??? 
cheers

retro baz · #6 Post by **retro baz** » Mon Mar 29, 2004 5:46 pm

i have topped up the oil and still no overdrive. 
i brung my multimeter home from work but the i fogot to charge it up today and its dead so i will have to wait until tomorrow. 
if it is an electrical problem will it hard the car at all driving it around???

Richard the old one · #7 Post by **Richard the old one** » Mon Mar 29, 2004 7:35 pm

I am not an expert but I believe that as the 12volt supply is used to energise the solenoid and so operate O/D if it is not there you can not do any damage. 
 
The only time that there is a problem is when the solenoid sticks and the unit stays in O/D when it should have dropped out. When this happens you will damage the unit if you reverse the car. 
 
I am awaiting with interest to hear what you find out tomorrow when your multimeter is charged. 
 
All the best 
 
Richard the old one

Matt Cotton · #8 Post by **Matt Cotton** » Mon Mar 29, 2004 8:21 pm

Got my box in at the weekend and am pleased to report all is well..sort of! 
 
Seems a bit noisy in 3rd gear, but overdrive now works. 
Had to check all connections with a multimeter myself as it wouldn't work at first. 
 
If you find the loom is in poor condition from gearlever switch to conection with main loom, then Malc has some new ones in stock that I got hold of. 
 
Also if you have the car in 3rd or 4th and engauge o/d you should hear the solenoid 'click'. 
 
Makes a big difference, should have converted long ago!

adu3b · #9 Post by **adu3b** » Mon Mar 29, 2004 9:10 pm

hope you dont mind me coming in if you are on a 1500 hl you should have a j type od this means you wont have a relay feeding it it bis straight wired as such through the ignition the problem we have found b4 is that the reverse switch is also part of the inhibitor and as such if it goes wrong can cause a los of overdrive might be worth checking it for contiuity regards mark jigsaw

retro baz · #10 Post by **retro baz** » Mon Mar 29, 2004 9:44 pm

sorry mark, 
i sort of understand but what am i checking exactly???

adu3b · #11 Post by **adu3b** » Tue Mar 30, 2004 8:29 am

you will find at the bottom of you gear lever where the lever clips on to the box there willbe a small black or brass couler switch on the left if i remember right this is your reverse light switch but also acts as an inhibitor to your overdrive

Jon Tilson · #12 Post by **Jon Tilson** » Tue Mar 30, 2004 9:12 am

The reverse light switch has nothing whatever to do with the overdriive circuit. Have a look at the wiring schematic. I accept it takes a 12 v feed from the same connector but thats it. From then on its just in parrallel and has no bearing whatsoever on the overdrive. The inhibitor on top of the box only allows the o/d electrics to work in 3rd and 4th. IIRC its in the circuit before the gearstick switch on a single rail box....so it goes power to inhibitor in series with stick switch to solenoid to earth. The box loom branches before the inhibitor to provide power for the reverse light switch. 
Jonners

retro baz · #13 Post by **retro baz** » Tue Mar 30, 2004 4:40 pm

ok driving to wotk after dinner and i flicked my swich praying to god it worked (which i have done every 5 minutes of driving) and it did. 
i topped it up with oil and did 20 odd mile to test it but no luck last night. 
the only possible explanation i can think of is that there was an airlock in the gearbox and it has self bled and now works. 
does this sound a good idea or does anyone know the real truth???

adu3b · #14 Post by **adu3b** » Tue Mar 30, 2004 6:44 pm

try disconecting or useing a knakerd switch then jonners and see if you od works

Richard the old one · #15 Post by **Richard the old one** » Tue Mar 30, 2004 9:59 pm

Retro baz 
 
I suspect you will never know with any certainty until it plays up again. I was expecting you to be advising that it was the switch on the gear stick 
 
In respect to the reversing light switch having an effect on O/D I have to agree with Jonners. It should not but by moving the reversing light wires this may have at the same time moved the O/D wires and as a result sorted the problem if say it was a bad connection. 
 
The joys of motoring.

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