Road speed sensor test

[schueymcfee]

I have a LT77 Rover gearbox with the road speed sensor. My speedo has stopped working, although when tested it works fine. So I'm presuming it's the road speed sensor. How can I test it before I start taking the exhaust off etc?

Also, that is the only speed sensor right? There isn't one on the diff like the newer Borg Warner versions?

Thanks.

[HarryW]

If you have access to a fault code reader then it should also register a fault in the ECU. AFAIK the only thing it will effect is the the ECU control of the engine whilst changing gear and slowing down, you may even experience stalling whilst pulling up similar to a dirty/shagged stepper motor.
Have a look at the bible electrical drawings you should be able to pick up the wire somewhere, the output is AFAIK a pulsed 12v one.

Harry

[K4TRV]

schueymcfee said:

snippity.... Also, that is the only speed sensor right? There isn't one on the diff like the newer Borg Warner versions? .....Snip Thanks.

I'm at work so don't have "Bible" at hand.

But I also have early Chim with Rover Box. My version does not use anything on the Rover box (it does have the provision at the rear for cable driven speedo like TR7). Mine has/uses a sensor attached to nose of Diff - thought ALL chims came like that. Suggest you get under and have a look - don't need to take exhaust off as it's behind and up next to Diff - You may need "long arms" !!

Trev McM

[schueymcfee]

K4TRV said:

schueymcfee said: snippity.... Also, that is the only speed sensor right? There isn't one on the diff like the newer Borg Warner versions? .....Snip Thanks. I'm at work so don't have "Bible" at hand. But I also have early Chim with Rover Box. My version does not use anything on the Rover box (it does have the provision at the rear for cable driven speedo like TR7). Mine has/uses a sensor attached to nose of Diff - thought ALL chims came like that. Suggest you get under and have a look - don't need to take exhaust off as it's behind and up next to Diff - You may need "long arms" !! Trev McM

Thanks will have a look tonight. What's it look like? Is it big? I hammerited and waxoiled my my chassis over the winter so maybe I've covered the sensor up on the diff.

[schueymcfee]

HarryW said:

AFAIK the only thing it will effect is the the ECU control of the engine whilst changing gear and slowing down, you may even experience stalling whilst pulling up similar to a dirty/shagged stepper motor. Harry

I do have that problem too!