Overdrive light

Q The overdrive light is coming on when driving my 2000 Ford Explorer North Face 4.0 auto. It shows up as a flashing light on the dashboard and will not stop unless you switch the engine off and back on, then it might stay off for 500 miles or come back in minutes. Sometimes you could do a 200-mile journey and it won’t happen or it could happen after five miles. The overdrive button on the gearshift has no effect on it and, if you use this button to turn off the overdrive, the light is on constantly.

I have been told it could be the ECU, wiring or solenoids in the gearbox. Could you shed any light on this? Also, do you know of a code reader that would work with this? I tried to get the codes read and a couple of garages couldn’t do it with their expensive equipment. Stan Lurkins

A Starting with the code reader, this depends on whether the Explorer is imported or a European model. If it is imported, then it should be compliant with Obdiicompatible code readers – federal requirements apply to all vehicles sold in the US since 1996. If it is of European origin, it will not necessarily be compatible with EOBD requirements, as the compliance didn’t come into effect until 2001; this compliance is only applicable to onboard engine systems and does not cover the gearbox, ABS, airbags, etc. Having said that, most modern professional scanners should be able to interrogate the software. You should check that the live feed to the OBD plug is operational – this is powered by fuse 17, the same fuse as the 12V socket.

One common problem with the Explorer is that the overdrive light flashes and may store codes ‘P0741’ and ‘P1740’ in the ECU memory. This is normally caused by a damaged torque convertor clutch solenoid valve. When this problem occurs, it is normally accompanied by a shudder through the drivetrain when pulling off and slowing down. Replacing the solenoid valve should rectify it.