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Odometer stopped working


jack cottam
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Doh! Just had the car MOT'd and they must have poked about underneath 'cos my odomter and trip meter has stopped clocking up!

 

I am told there are two sensors on the gearbox - one for the speedo and one for the odometer but the only tools I have is a knife and fork ( and the knife's blunt! )

 

Anyone know where I can take it - I am post code GU51 - Fleet in Hampshire...

 

Thanks

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Hey, I work just round the corner from you, on the junction of Fleet Rd and Kings Rd.

 

Your tools will be handy for lunch, but not much else! :D

 

The odometer uses the speed sensor's signal to increment the number it displays. Do any digits show on the display at all?

 

We can have a chat about it if you want.....

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Hi guys - thanks for the info. I will try the disconnecting the battery.

Stevie - if this doesn't work I'll get in touch if that's OK. All the digits are showing - just not moving ( bit like me really )

 

JohnC - I just moved to The Heath I will slow dow . I've also seen the red one and another black one too.

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JohnC: there used to be 2 others where I work. I think there's only one other now. I've also seen one in the Ravenscroft garage, presumably for a service....

 

jack: no problem. Do the battery thing first. Let us know what happens, it'll help others (me included!) learn from it.

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Hi Jspec Germany, did you get your odo problems sorted out? If so, what did you do?

 

No, I haven't sorted it yet. Still giving me a code 42 with the Thor TSD wired in at the ECU and still limited. I need to pull it all apart and rewire behind the speedo. There's several threads that talk about how to do it, although confusing. It's just a matter of pulling the dash apart and doing it. Been too busy with work and school. Will try and knock it out and post results.

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No, I haven't sorted it yet. Still giving me a code 42 with the Thor TSD wired in at the ECU and still limited. I need to pull it all apart and rewire behind the speedo.

 

That kind of follows. As you said, I think the TSD is wired in at the ECU, which is electrically "downstream" from the odo and (assuming the odo or speedo output is at fault) hence after where the fault initially occurs.

 

Have you tried bypassing the odo's buffer circuit? It's a mod that can be reversed by using a soldering iron.

 

(The combined Thor TSD/DSC or just the DSC on its own gives you the bypass-buffer mod "for free", but of course you don't want a DSC in Germany.)

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I'm in Fleet during the day: I could take a look one lunchtime if you wanted, but there's probably not much I could do in that time. First thing's first: does the engine warning bulb light up constantly (no flashing) when you test for error codes?

 

If it does, and your speedo works, then it means the speed signal reaches the odometer and can leave it, but doesn't get processed within it. I'd try having a poke around behind the odo unit. If you're around during lunchtime, PM me and I can at least show you how to get the odo out.

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  • 2 years later...
Guest MKIV-Germany

I have got the same problem.

My odometer doesn't work. The digits are displayed solid. I already tried disconnecting the battery - doesn't work.

 

I have a Apexi Power FC in my car. I don't know if it might be a problem with that...

 

Do you have any tips for me? Should I check the sensors?

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The digits are displayed solid

Do you mean the display reads "888888" with all segments lit? If so that's a strange symptom that I've never heard of before.

 

I have no knowledge of the Apexi so I can't say if that could cause it or not.

 

It's unlikely to be a sensor problem. Do you have any error codes logged? Code 42 I would guess, but if you have any others it might give some clues. Unlikely, but worth doing for the time it takes. If your speedometer works then it's almost certainly not a sensor problem. I would guess either the Apexi or your odometer unit has got a weird electrical short in it.

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Guest MKIV-Germany
Do you mean the display reads "888888" with all segments lit? If so that's a strange symptom that I've never heard of before.

 

My odometer reads 59900 km and doesn't move on.

The trip meter reads 0 km after resetting.

A few days ago it read 0.1 km. Strange... It seems to work somehow, but not right ^^

 

If your speedometer works then it's almost certainly not a sensor problem. I would guess either the Apexi or your odometer unit has got a weird electrical short in it.

 

The speedo works. It's a TRD 320 km/h speedo.

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In that case there must be a break in the wiring between the speedo and the odometer, or the odometer is faulty (dry solder on the printed circuit board probably). I'd pop the dash panels off and visually check the wiring behind the speedo and around the odomoter. Sorry that's a bit vague: I can't remember exactly which wire sends the signal from the speedo to the odometer.

 

The speed sensor passes its signal to the speedo. The speedo displays the speed, then passes the signal onto the odomoter. The odometer uses it to count up, then passes it onto the ECU in the passenger footwell. The sensor, speedo, odometer and ECU are connected in series, so if a fault occurs along the wiring or with one of these components, everything "downstream" will report a fault. If something works, everything "upstream" of that is almost certainly working too.

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Guest MKIV-Germany
In that case there must be a break in the wiring between the speedo and the odometer, or the odometer is faulty (dry solder on the printed circuit board probably). I'd pop the dash panels off and visually check the wiring behind the speedo and around the odomoter. Sorry that's a bit vague: I can't remember exactly which wire sends the signal from the speedo to the odometer.

 

The speed sensor passes its signal to the speedo. The speedo displays the speed, then passes the signal onto the odomoter. The odometer uses it to count up, then passes it onto the ECU in the passenger footwell. The sensor, speedo, odometer and ECU are connected in series, so if a fault occurs along the wiring or with one of these components, everything "downstream" will report a fault. If something works, everything "upstream" of that is almost certainly working too.

 

Okay...

 

Means... My speedo works, so it can't be the speed sensor. Right?

The odometer only shows 59900 km and doesn't count up, so it might be the wiring... Which colour is the wire for the speed signal to odo?

 

Regards

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Means... My speedo works, so it can't be the speed sensor. Right?

Right. :)

 

The odometer only shows 59900 km and doesn't count up, so it might be the wiring... Which colour is the wire for the speed signal to odo?

In post #9 of this thread, there's a wiring diagram for a Thor speed converter. Looking at this, I think the speedo's speed signal output to the odometer is pin 5 at the speedo, and that connects directly to pin 5 on the odometer plug, making pin 5 the odometer's speed signal input.

 

Bit of background, probably not needed:

The speed signal is a pulsed voltage whose frequency is proportional to the speed, not a steady voltage whose voltage is proportional to the speed. IIRC there's 4 pulses per revolution of a road wheel.

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