The engine cuts out when the overdrive is switched on! Any thoughts?

[Guest Pipnchick]

Apologies if you are reading this for the second time. I first posted it mistakenly in the new members forum.

 

I recently had the odd starting problem whereby the engine would spin over happily on the starter but wouldn't fire and run. Later in the day it would start perfectly. This happened more often over the following couple of weeks until it wouldn't start at all. I finally worked it out that if the overdrive was switched off, it was perfect! Sure enough the car runs with the overdrive off but cuts out completely as soon as the overdrive is turned on again. Hence I have in effect no 4th gear. Having left the car for a week It was fine for a couple of days but has now reverted back to cutting out in overdrive. No warning lights have illuminated and I've topped up the ATF to the correct level. I am about to wiggle any wiring connectors to sensors around the transmission as my first step, does anybody have any more ideas or have experienced a similar problem? I've searched the forums but have not found the same problem. The Supe is a 1993, auto, non-turbo, absolutely factory standard which I've owned for 12 years. Any thoughts as to which direction to head would be much appreciated.

[chrispot]

I don't know what the problem is but i would first check all the earth points with the ecu ( shown in the manual) then do a continuity check for od switch to ecu etc. maybe a short in the od switch to earth? killing the ecu. let us know what you find. good luck and regards chris

[Guest Pipnchick]

Hi Chris, Your advice kinda ties in with that provided by SPG on my post in the new members forum so very encouraging. I noticed this evening that even when the engine runs in both OD on and OD off, switching between the two causes it to drop in revs/hesitate momentarily so I feel that may also fit with your and SPG's thoughts. I'll check out the wiring and earth points over the weekend and will let you know how I fare.

Many thanks,

Pip

[Ian C]

Check earth point IE, located in the drivers' side kick panel, high up with the fuse box. Nightmare to look at, but it's directly connected to the overdrive switch.

[Guest Pipnchick]

Hey thanks. It sounds like one of those I may never have found without your advice. I've been slacking badly over the weekend but will get to it soon and will report back.