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cla5h · Post by **cla5h** » Fri May 25, 2012 4:09 pm

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BiggestNizzy · Post by **BiggestNizzy** » Fri May 25, 2012 4:16 pm

http://www.scottishelises.com/phpbb/vie ... or#p368425

I think I got mine on ebay

cla5h · Post by **cla5h** » Fri May 25, 2012 4:20 pm

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BiggestNizzy · Post by **BiggestNizzy** » Fri May 25, 2012 4:26 pm

My old man did it

cla5h · Post by **cla5h** » Fri May 25, 2012 4:53 pm

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cla5h · Post by **cla5h** » Sat Oct 13, 2012 3:03 pm

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tut · Post by **tut** » Sat Oct 13, 2012 6:06 pm

Mine went like that five years ago Steve, replaced the sensor and still no go, so left it. Now with the Honda engine, the CV joint does not have the toothed wheel on, so will never work anyway.

Robin made me up a magic gizmo to wind the mileage on for MOT's and Insurance, I use the tacho for speed, so not bothered about no speedo. Mileage does not count with my car as it has reached a quarter of a million miles, and I am not cheating anybody as I am not winding the mileage back and quite happy to state genuine mileage.

tut

robin · Post by **robin** » Sat Oct 13, 2012 7:38 pm

With the S2 (is it S2?) the speed setup is different - the wheel speed sensor feeds the ECU and then ECU feeds the speedo.

If you observe carefully you can tell whether or not the ECU knows that the wheels are turning once warmed up.

Find a downhill section where you can safely stop and safely coast without causing obstruction/risk/blah blah.

With the car warmed up and stationary pointing downhill you should have normal idle speed of 800 RPM or so.

Now leave in neutral and release handbrake so car starts to roll down the hill. If the ECU is seeing pulses from the sensor then when you reach a couple of mph it should increase the idle speed to 1,000 RPM or so.

If that doesn't happen then the ECU isn't seeing the pulses from the sensor. You should check continuity of the sensor first using a multi-meter. Split the connector (or terminal block or whatever you're using now) Measure the resistance between the two wires that run to the sensor - you should see some resistance less than 10Kohm I believe. If you see open circuit of much higher than 10K the sensor or wiring to the sensor is bust. Now flip to voltmeter setting - 20V range is OK - turn on ignition and with connector still split measure the voltage between the two wires coming from the vehicle. You should see a small positive (or negative if you've got probes back to front) voltage - it doesn't actually matter what voltage so long as there's a voltage. If you see nothing then the wires to the ECU (or, unlikely, the ECU itself is bust).

My money would be on wires first, sensor second, ECU third.

If the ECU is seeing pulses from the sensor (rolling idle increases) then the speedo is faulty - perhaps the needle has come off the spindle or there is a cabling fault.

Cheers,
Robin

cla5h · Post by **cla5h** » Sun Oct 14, 2012 5:34 pm

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robin · Post by **robin** » Sun Oct 14, 2012 8:15 pm

I suspect it's not the wiring in that case - the faster the wheel rotates, the larger the magnitude of the pulse from the sensor - chances are that the sensor gap to the toothed ring on the drive shaft is either clogged with some gunk or the sensor has moved somehow - now you need faster wheel speed to get the required pulse amplitude to trigger the VR detector circuit in the ECU.

I think the sensor is integral to the wheel bearing on the S2 though it might be possible to replace just the sensor?

Cheers,
Robin

cjm · Post by **cjm** » Mon Oct 15, 2012 11:37 am

Hey Scott, I'm sure I have a multi-meter in the flat if you want to borrow it or need a hand.

cla5h · Post by **cla5h** » Mon Oct 15, 2012 7:44 pm

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robin · Post by **robin** » Tue Oct 16, 2012 8:05 am

Hmm. From my analysis of the S2 ECU's wheel speed circuit I would expect to see a small bias voltage on the positive wire relative to the negative wire - however, I could be wrong. The wheel speed sensor should definitely have some resistance when measured with the multi-meter because it's just a coil of wire, really. I think all the S2's have a wheel speed sensor on each wheel even though only one is wired and used - so you could measure the resistance of one of the others to confirm that there should be a resistance.

Cheers,
Robin

cla5h · Post by **cla5h** » Thu Oct 18, 2012 11:48 am

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robin · Post by **robin** » Thu Oct 18, 2012 1:13 pm

I believe that the MIL only comes on when there is something wrong that will affect emissions. The ECU will store codes for all faults, whether or not emissions related. The speedo doesn't have an impact on emissions (and in fact the K4 ECU doesn't even know whether or not the speedo is present). If the ECU cannot see the wheel speed sensor it cannot adjust the idle speed for stationary idle (lower) vs rolling idle (higher) and this does impact emissions, hence the MIL.

That's my theory anyway

According to my (ancient) S2 service manual there is only one fault relating to speed sensor which is P0500. It is triggered by the engine turning at <3000 RPM with the throttle shut (i.e. on the overrun); if it sees this condition for 2 seconds AND reads <3mph from the wheel speed sensor then it knows the sensor isn't working. If this happens twice then it stores a code. Interestingly it does not say that this fault will be indicated by MIL, so your MIL could be on for some other reason.

Get the codes read and post them up ...

Cheers,
Robin

Scottish Elises

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