No speedo reading at ECU

Been getting into the ECU (Lucas) to try and find the cause of poor running - of which more another time.

But my first problem is that the ECU is not getting vehicle speed data. The transducer is working OK, and the speedometer is fine, but Roverguage shows no movement on the ECU speed reading.

The transducer here is fitted direct to the transfer box, not one of those inserted into the middle of a mechanical cable. I have seen somewhere that there is a relay which uses the feed from transducer to speedo to activate the signal to the ECU, but I can't find any info (and Rave is no help).

Is anybody familiar with this system?

What Year??

Oops. 1994

does the eas work proper?ie drop from high to normal at 35 or drop from normal to motorway level at 55?

if it does then transducer and signal conditioning (the relay that isnt a relay)is good .

If I had any idea what eas meant I might be able to tell you!

Electronic Air Suspension...

That explains why I didn't understand. Don't have the air suspension - mine is a classic, softdash, proper springs. Don't like any later models, and may well go older for next vehicle.

So do I still have this "signal conditioner"? Where is it?

From the 1992 LSE and the 1993 Vogue SE had Air Suspension on the Classics!

I'll see if I can find the 1994 Wiring Diagrams!

Thanks. I often seem to have this sort of problem with this vehicle. Registered 1994 - but when was it built? Seems to be a bit of a hybrid.

When the rain stops I will see what the VIN is.

From 1993 onwards i should have said....the Vogue SE had EAS iirc.

According to the VIN mine is a 1991 model. Actually first registered April 1994. Does this help?

Yep - cos there were many wiring changes in the later classics....and in 1991 you won't have the EAS either!

Download this from my Drop Box account....it is quite a bit of information for the various Classics!

Hope it helps...

https://www.dropbox.com/s/kzvpm11vbadnl0w/RR_Classic_84_96_WSM.rar

Thanks for that - going to take a while to get to grips with it though!

Land Rover builds being weird as usual!

I am now pretty certain that on my machine the road speed is not transmitted to the ECU - no fault, the ECU programming version just does not use it.

Certainly, now I have corrected the massive air leak at the plenum chamber, she is running as well as ever, and just passed MOT with negligible emissions - so I think I will leave well alone.

Thanks for all the advice - I expect I will be back next time she misbehaves.

Oldfogey said:

Land Rover builds being weird as usual!

I am now pretty certain that on my machine the road speed is not transmitted to the ECU - no fault, the ECU programming version just does not use it.

Certainly, now I have corrected the massive air leak at the plenum chamber, she is running as well as ever, and just passed MOT with negligible emissions - so I think I will leave well alone.

Thanks for all the advice - I expect I will be back next time she misbehaves.

Click to expand...

If yours is a '91 you will find some parts aren't what you expect. AFAIK '91 was a change over model year, for example, my '91 has early ABS front axle but can also have the later type.

Anyway, the speed transducer sends a signal to the ecu which is used to turn on and off the idle stabilisation. If the ecu doesn't see a road speed signal you will have idle problems, also the injection warning light will come on. The speedo will not work if the transducer dies and nor will the cruise control.

Anyway, glad you found an air leak and got it running better.

I spend a lot of time on IT forums, so I know how frustrating it is when there is no feedback on a problem!