Speed sensor

[Garyc]

Help!!! My hybrid brings up an EMF fault once it goes over 20mph, code relates to a speed sensor fault but my local garage who are hybrid specialists and generally very good are struggling to get any information, they believe the fault may be a gearbox speed sensor but access is restricted, the fault only appeared when I changed the head unit but not sure it's related, anyone got any ideas or information that may help, car drives exactly as it did before the fault occurred.

[Jeza]

What about the cruise control you fitted, has that done something to the speed signal?

[Garyc]

Still doesn't work, the speed sensor fault appeared first so I think it might be related, begrudgingly I have purchased the official wiring diagram and service manual, waiting on delivery from Japan 

[Picasso]

hi speed sensor is on the gear box there is 2 if you pm me your reg no. i will give you the part no.s and the a drawing where located

[Garyc]

Lf56wke the garage says one of the sensors is behind the hybrid workings so access is an issue , thank you for your help, much 4.

[Jeza]

DTC P0500 is a vehicle speed fault, not a gearbox speed sensor issue. Gearbox speed sensor faults are DTC P1820 and P1825.

The speed signal comes from the wheel speed sensors to the skid control computer then to the combination meter, from there is a wire to the engine ECU, head unit, power amplifier and cruise control. Possibly in that line also is a chip to convert kph to mph.

As the issue occured after installing your new head unit I would look at the speed signal wire to that. Grey connector, pin 3, violet colour

[Garyc]

Thank you so much, that's the most information I have had and makes a lot of sense