overdrive rover P4 100 not working

Huo

New Member
#1
The overdrive on my old p4 100 has stopped working, checked circuit all seems ok power to switch on top of gearbox when 4th gear is selected, solenoid switch on back of gearbox, i took it off and connect 12v it operates. all this since i replaced servo, but forgot to disconnect battery although all fuses intact occasionally overdrive fuse blows, any suggestions.
 

roverp480

Active Member
#2
The overdrive on my old p4 100 has stopped working, checked circuit all seems ok power to switch on top of gearbox when 4th gear is selected, solenoid switch on back of gearbox, i took it off and connect 12v it operates. all this since i replaced servo, but forgot to disconnect battery although all fuses intact occasionally overdrive fuse blows, any suggestions.
The solenoid is has a two stage operation, with two operating coils. Both operate to pull it in and then points on the end open, to disconnect one of the coils so there is a low current holding it . Check that the points are clean and that both coils are working, it should operate with a very sharp clack. My P4 80 had this issue & cleaning the points on the end bought both coils into play and problem solved. The holding coil on its own isn't usually sufficient to operate it , although off the vehicle it will appear to work.
 

Huo

New Member
#3
Hello
Thank you for the info I have just taken solenoid off removed rubber cover. The points end are fully shut so opened up a bit and cleaned I tried passing current through it but doesn't seem to be any life now ...
Might need new one.
 

roverp480

Active Member
#4
. When you say "so opened up a bit and cleaned" , I presume they are closed when at rest . Points should be closed when solenoid at rest and open when it is actuated and at end of travel .
 

Huo

New Member
#5
Oh dear think I adjusted slightly open at rest!
Will have another look doesn't seem to be getting any power to solenoid when on car. Any other suggestions. Just taken switch /lever on steering column apart and refited very fiddly seems to be working better, but no clonk on solenoid .mmmm... Thanks for taking time to message much appreciated.
Regards.
 

colnerov

Well-Known Member
#6
Oh dear think I adjusted slightly open at rest!
Will have another look doesn't seem to be getting any power to solenoid when on car. Any other suggestions. Just taken switch /lever on steering column apart and refited very fiddly seems to be working better, but no clonk on solenoid .mmmm... Thanks for taking time to message much appreciated.
Regards.
Hi, If there's no power down to the solenoid you don't know whether the solenoid is faulty or not yet. The column switch might be 'working better' but is it working electrically? Is there power to and from the switch? If yes then find and check the relay for power. Before going onto the solenoid. Basically you need to follow the power, switches including column, throttle linkage and gearbox to relay and then to solenoid.

Colin
 

roverp480

Active Member
#8
In my view it is unlikely the column switch is at fault .Remember the switches on the throttle have to be set properly as per the book and the overdrive solenoid will only actuate in 4th gear , and with the throttle part open, not closed or full throttle .
 

Huo

New Member
#9
Hello
Update on my overdrive problem. Have reset the solenoid so closed at rest also adjusted T switches on throttle...the horizontal one has a prob the connection on the brown wire does not seem to show any power ..tested all others light up with overdrive engaged any thoughts regards Pete
 
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