Hi, for some reason, occasionally, in slow moving trafffic (ie low gears, slow speed, stop/start) I get a "transmission fault - limited gears" message. If I switch off, go into P, give it a minute and start up again, everything is fine.

The first time I thought, oh, its the gearbox, but actually the gearbox is fine, changes smoothly, finds gears ok. Also, i can't trigger this error to come on if I try - it seems to be some quirk combination of hot engine, low gears, switching between D/N, stop/start, on and off the break pedal that seems to make it get confused or something.

Maybe some kind of ECU or sensor error, mechanically everything seems fine, and after "resetting" again its fine again.

This only happens in creeping traffic. Just wonder if anyone had this same issue, and got to the bottom of it?

Any words of wisdom will be much appreciated!

(4.2 S/C 2005)

Maybe new radiator required. The bottom levels get gunked up and this is where the tranny oil cooler is run off from (in some models. Can’t say it’s the same in yours)

How old is your battery?

Phil

same year as mine did the same with a failing battery

The battery is a top of range bosch one only 6 months old, so if it's electrical it's to do with circuitry rather than failing battery. Also if I do diagnostics it doesn't seem to have logged as a proper fault.

Also it can happen before the engine/gearbox has had time to heat up, although I will investigate the radiator option further.
The thing that it seems to coincide with most is low speed and low revs in D and frequent changes to N. All of a sudden Bong! Bong! Bong! Stop, switch off, P, start up, back to normal.

The radiator/overheating issue was on 5-speed vehicles.

Does the error message consistently appear just when you move the gear lever e.g. indicating a gear position/inhibitor switch fault on the Mechatronic unit?

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phil, slightly off topic and re your last statement, is it preferable to leave in 'd' in stop/start traffic?

Just personal preference, really. I must admit that I can’t be bothered to select neutral for short stops. It doesn’t matter to the transmission if you leave it in ‘D’ because the turbine shaft is stationary, so the running gear doesn’t see any fatigue cycles. The additional thermal load on the fluid from the stalled converter is trivial at tickover. The downside is a slight penalty in fuel economy (as the engine idle speed control has to fuel the engine to overcome the additional converter drag) and annoying the driver behind you with your brake lights! The later 8-speed boxes introduced Neutral Idle Control to automatically disengage gear if the car was stationary with the driver’s foot on the brake, to improve fuel economy.

In Dustbolt’s case I just wondered if it might be worth experimenting leaving ‘D’ selected, and not moving the gear shift into neutral when you stop, to see if this prevents the error message from coming on.

Phil

excellent, thank you phil.....

Hi Phil, thanks for taking the time to reply.
Yes I tend to put it in N in stop start traffic conditions, just because I had a vague idea D plus break pedal was bad somehow. I will just leaving it in D from now on in those conditions and see if it ever happens again. If that fixes it, it would seem to suggest the mechatronic switch is root causes.