Ollie Posted June 13, 2014 Report Share Posted June 13, 2014 Can anyone help? I am really struggling on this one... My overdrive has developed a really annoying intermittent problem where it doesn't always engage and I can't think of any obvious reasons. The symptoms are: The problem occurs at anything between a couple of miles of running up to about 40 (so far). However, I went out in it this week for over 70 miles and had no problems. There is no obvious pattern except that when it doesn't work, if I leave it overnight it works in the morning (at least for a short while) The overdrive can be working normally and at some random point when the column switch is engaged the overdrive doesn't do anything. Even if the column switch is left 'on' for a long time, the overdrive doesn't engage. The lack of overdrive engagement can last for just a mile (or less) or carry on for several/many miles. When it comes back on it is as normal, as though nothing has happened. The overdrive does not disengage randomly - only when the column switch is turned off There are no untoward noises when the overdrive is engaged or not. The solenoid appears to be working - when I have checked it at stop it 'clicks' and draws about 2 amps Interestingly, when the overdrive is engaged in 3rd gear it is sometimes (but not always) a bit hesitant, almost engaging in stages; 4th gear always appears to be as normal, going straight in. There has been a time when it did not engage in 3rd, but when I immediately changed into 4th and tried again, it worked. This may have been coincidence Oil levels are ok in the box I don't have a pressure gauge to check the hydraulic pressure, unfortunately Any help would be much appreciated. Thanks Ollie Quote Link to post Share on other sites
Peter Cobbold Posted June 13, 2014 Report Share Posted June 13, 2014 Ollie, Sounds electrical to me. Clean the connector at the solenoid first, also to the on-off switch. If that doesnt work, then check the bunch of connectors above your left foot, coming out of the transmission tunnel. Finally,the switches on top of the gearbox - the transmission tunnel cover has to come off. These switches ensure the o'd only works on 3 and 4, there's not a direct wire from the on-off switch to the solenoid. Peter Quote Link to post Share on other sites
graeme Posted June 13, 2014 Report Share Posted June 13, 2014 Ollie, There is only one permissive switch on the J type O/D and it needs to be adjusted correctly to operate reliably. I would be looking there first. Graeme Quote Link to post Share on other sites
Agile Posted June 13, 2014 Report Share Posted June 13, 2014 Hi Ollie, Having had a similar intermittent problem, I found it relevant to measure the current (in my case also about 2A but slightly reducing over time). Try to capture the current during an error situation. Does it drop to zero? Electrical problem! Follow Peter's tips! In my case (J type) there is a relay, so it should be relatively easy to measure the current by accessing the terminals on the relay. Anyhow, you measured the current, so likely not new to you. To complete things, you could also measure the voltage across the solenoid (measure on the solenoid terminals). That should allow you to conclude if it is an electrical problem or not. Note: in my case, the relay is controlled by the steering column switch obviously but also by the switches on the gearbox indicating 3rd or 4th gear. You indicated different behavior depending on 3/4 gear which indeed suggests electrical. If it not an electrical problem, let the forum speak! Ps in my case it was electrical, the grounding wire from the solenoid was bad. Reason why a current measurement turned out relevant. W. Quote Link to post Share on other sites
RonA Posted June 14, 2014 Report Share Posted June 14, 2014 Hi I had similar symptoms to yours several years ago, it was due to a dodgy column switch, the biggest problem was getting an aftermarket switch that was any better, I eventually made my own using a modern switch grafted to the original stalk. Best of luck RonA Quote Link to post Share on other sites
Ollie Posted June 15, 2014 Author Report Share Posted June 15, 2014 Thanks for your suggestions which i will be following up on. I also thought it may be electrical and will check on the areas you have suggested. Thanks again Ollie Quote Link to post Share on other sites
brucer Posted June 15, 2014 Report Share Posted June 15, 2014 If you are doing continuity tests do not trust a digital multimeter they give false results. Use a bulb and battery. (ask me how I know ) Bruce Quote Link to post Share on other sites
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