Speedo cuts out, then comes back to life

[Hodgins]

Bit of a strange one this, been happening for a while but curiosity is getting the better of me,

I havent had it plugged in yet,

Basically ill set off, and then ill get to 30mph
The stop and handbrake light will come on, stay on, and the speedo will drop to 20mph

Give it a mile down the road or sooner if in take a corner lol and itll spring back to life
And will behave as normal for the entire duration of any journey in it,

It happens within the first few metres if i leave for work, come to life at first roundabout then is fine for the 30+ mile on the commute

Im thinking its abs sensor based (ph2 car) but i cant get my head around why it comes back to life and is then fine, it does this every day lol
Surely if something was broke, itd be broke constantly

I understand i need it plugged in to see whats fully going on but just wondered if anyone had any ideas

Cheers

 

[Stay Puft]

I had this exact thing. Just a speedo sensor for about £20.

 

[Hodgins]

@Davyy thanks for the response, i always thought that ph2 cars take speed reading off the abs or is there another sensor?

Forgot to mention its a non sport

 

[Stay Puft]

I get confused as to what is what.. Rentech did mine and diagnosed it.

 

[Ads29]

I'm not 100% on the non sport setups, but for the sports there were a couple of options.

The earlier ph2 sports and the cup versions (as they don't have abs) have jc129 gearboxes, which use a speed sensor attached to the gearbox as in the photo above

Later ph2's ran with jc130 gearbox which uses the abs system to determine vehicle speed via front wheel sensor, I believe an easy way of checking is to see whether the car in question has traction control as only the later 130 gearboxes used traction, although I may be wrong

Hope it helps

 

[Stay Puft]

I didn't know I didn't have abs

 

[Gus]

Most likely will be the sensors as above.
Speedo not working intermittently has happened to me in the past and it has been due to:
Earth strap to gearbox.
another time it was down to weak battery and alternator not working properly.

 

[Ads29]

I didn't know I didn't have abs 😧

Doesn't mean you don't have abs, my sport is an 02 plate which has the early gearbox and abs as well