Speedo reads when stop at lights

[5.0 ED]

Everynow and then when parked at traffic lights my speedo jumps up, sometimes 40, sometimes 20.

Now i thought the earth's under airbox were partly resposible so i've redone them all, but still prob, also oil gauge is a bit low on reading some times to, anyone know where to look?

[Stav]

Mine does the same thing too. Don't know why. I suspect a bad earth,speedo transducer playing up ?

I ignore it..the car keeps going ,the radio drowns out the rattles and I am a very happy ford driver again.

[mattp]

Mine used to do this, I cleaned the contacts on the plug that goes into the passenger side of the gearbox, seems to have fixed it (hasn't done it in a year or so). I just unplugged it and sprayed it with WD40 then plugged it back in. Easy.

[JC]

Originally Posted by mattp

Mine used to do this, I cleaned the contacts on the plug that goes into the passenger side of the gearbox, seems to have fixed it (hasn't done it in a year or so). I just unplugged it and sprayed it with WD40 then plugged it back in. Easy.

Yep, that's what fixed mine when my AU Xr8 was doing the same thing.

[5.0 ED]

hmmm interesting cause the plug in the side of the gearbox has nothing to do with the speedo, the speedo is at the back with a red covering on the wires. but anyway i'll try cleaning it and see what happens.

Cheers.

[sly]

Mine has done the same for a while. I dread it happening... when I had the cam & chip in, after a few weeks the speedo would start doing this... more & more frequently, then the engine would start going into LHM and eventually the PCM would stop talking to the BEM and the car would have to be towed to a workshop and the PCM reflashed. Once the BEM ended up totally dead when this happened and had to be replaced.

Without the chip on the J3 port, the speedo will occasionally shadow the tacho in Neutral (same as it did before) but the other symptoms don't develop. I've gone 11 months since I last pulled the cam & chip out, and I've resisted the temptation to put them back in... a flash tuner with generic tunes has been like Nicorettes to me In that 11 months the car hasn't missed a beat...

[5.0 ED]

Interesting, its funny how things that don't really have anything to do with other parts seem to somehow effect them at times.

[sly]

Is that the plug for the sensor that detects the shift lever position? Mine is full of cow poo...

[5.0 ED]

I thought he was talking about the round plug that has all the solonoid wires in it.

[Mechan1k]

My AU did it on odd occasions (less after new rebuilt auto went in though) ... mainl in wet weather though.

The new BFII has done it once ... noticed it when idling with handbrake on ... as the warning chime sounded for the "handbrake on when moving" warning.

Hasn't done it since.