Help - My speedo's gone and so has the timing!
Discussion
I'm hoping someone can help me out with a problem that's recently developed. Bear with me as I attempt to explain.
After fitting some of Steve Heath's rear ARB droplinks my speedo became intermittent and finally packed up completely. Thinking I must have done something to the nearby speedo sensor I took a look, and one of the wires from the front of the car that fed the speedo sensor (via a connector) seemed loose. As the wires were moulded into the connector I had no way of reconnecting it, so I cut them all, intending to reconnect them using a new connector.
Stupidly I forgot to note which colour wires from the front of the car (black and grey) connected to the ones from the sensor (black and red). I tried all the combinations (I think), but no speedo. I couldn't get a voltage reading from either of the two wires coming from the from of the car which seemed odd. I tried supplying 12 volts to the sensor from an external source but again, no result and no speedo.
Temporarily admitting defeat, I reconnected the wires back up at a best guess (black to black, red to grey) until I had some way of testing the sensor. However, my alarm then started acting up and became difficult to arm and disarm. So I disconnected the speedo sensor wires completely.
That was yesterday and today a new problem developed. The timing seems off, and when I change gear at speed the car stalls. It's fine at idle, but not much fun when going around corners when the engine stops and the PAS cuts out.
I did some hunting around various forums and on the Chimp Pages there is a letter from someone who had the same two problems (duff speedo and timing) and claimed it was fixed by replacing the transducer, as this apparently has something to do with the speedo reading being used to tell the engine not to drop the revs too much when changing gear. You may have realised I am not the most technical person around.
So, after that long-winded explanation, is there any experts around that can cast any light on this matter? What is this transducer in question? What should I try next?
Thanks!
Gregg
After fitting some of Steve Heath's rear ARB droplinks my speedo became intermittent and finally packed up completely. Thinking I must have done something to the nearby speedo sensor I took a look, and one of the wires from the front of the car that fed the speedo sensor (via a connector) seemed loose. As the wires were moulded into the connector I had no way of reconnecting it, so I cut them all, intending to reconnect them using a new connector.
Stupidly I forgot to note which colour wires from the front of the car (black and grey) connected to the ones from the sensor (black and red). I tried all the combinations (I think), but no speedo. I couldn't get a voltage reading from either of the two wires coming from the from of the car which seemed odd. I tried supplying 12 volts to the sensor from an external source but again, no result and no speedo.
Temporarily admitting defeat, I reconnected the wires back up at a best guess (black to black, red to grey) until I had some way of testing the sensor. However, my alarm then started acting up and became difficult to arm and disarm. So I disconnected the speedo sensor wires completely.
That was yesterday and today a new problem developed. The timing seems off, and when I change gear at speed the car stalls. It's fine at idle, but not much fun when going around corners when the engine stops and the PAS cuts out.
I did some hunting around various forums and on the Chimp Pages there is a letter from someone who had the same two problems (duff speedo and timing) and claimed it was fixed by replacing the transducer, as this apparently has something to do with the speedo reading being used to tell the engine not to drop the revs too much when changing gear. You may have realised I am not the most technical person around.
So, after that long-winded explanation, is there any experts around that can cast any light on this matter? What is this transducer in question? What should I try next?
Thanks!
Gregg
The speedo sensor is not really that close to either the ARB brackets or droplinks (I know this as I had the whole lot off over winter to access the chassis for derusting and painting), so the fact that the problem arose shortly after may be coincidence, and you chastise yourself unfairly. That said, I always tend to assume it must be my fault too when things stop working after I have done someting on the car!
I was not aware of any link between the speedo sensor and the timing - but do not profess to understand the complexity of the electronics on a modern TVR (or any other car for that matter), so it may well be true.
Good luck with the diagnosis, and hope someone else can be of more help. At least if you can rule out some simpler things it will reduce the cost of getting it sorted professionally if all else fails.
I was not aware of any link between the speedo sensor and the timing - but do not profess to understand the complexity of the electronics on a modern TVR (or any other car for that matter), so it may well be true.
Good luck with the diagnosis, and hope someone else can be of more help. At least if you can rule out some simpler things it will reduce the cost of getting it sorted professionally if all else fails.
Hi
The speedo sensor does have some control over the idling, but NOT the timing. The timing is determined on the Griff, by the physical position of the distributor.
If the speedo sensor has come disconnected it could well upset the idling or off throttle characteristics of the car.
Have you tried resetting the ECU? (in the passenger footwell, above the battery) There's a large connector with a plastic spring clip one end. Disconnect this for a few seconds, this will reset the ECU, and may well solve your problems, as it was probably getting strange information from the speedo sensor and tried to adapt accordingly.
Resetting it, puts it back to default settings.
The transducer you speak about is another name for the speedo sensor located near the rear axle.
HTH
The speedo sensor does have some control over the idling, but NOT the timing. The timing is determined on the Griff, by the physical position of the distributor.
If the speedo sensor has come disconnected it could well upset the idling or off throttle characteristics of the car.
Have you tried resetting the ECU? (in the passenger footwell, above the battery) There's a large connector with a plastic spring clip one end. Disconnect this for a few seconds, this will reset the ECU, and may well solve your problems, as it was probably getting strange information from the speedo sensor and tried to adapt accordingly.
Resetting it, puts it back to default settings.
The transducer you speak about is another name for the speedo sensor located near the rear axle.
HTH
Cheers for the advice, I'll try resetting the ECU. When i mentioned 'timing' I did actually mean the 'idling', I tend to mix up technical terms easily.
Unless something has suddenly packed up for no reason, the only thing that seemed untoward was the loose wire that connected to the sensor. Does the connector that joins the speedo sensor's wiring to the wiring coming from the front of the car actually do anything apart from being a simple connector?
Unless something has suddenly packed up for no reason, the only thing that seemed untoward was the loose wire that connected to the sensor. Does the connector that joins the speedo sensor's wiring to the wiring coming from the front of the car actually do anything apart from being a simple connector?
I'm sure when I did ours the black went to red and the grey to black but I guess each will be wired differently. We had the connector at one end (on the sensor wiring) and just bodged onto this as the connector from the car end had been cut off for whatever reason. I actually bought the bits to replace the connector from the car end from Sumitomo. These are the bits you will need to do the job:
1 off connector (female) 6189-0129
1 off retainer 6918-0322
2 off terminals 1500-0110
2 off wire seals 7165-0135
Web link:
http://swsct.sws.co.jp/index_e.html
I would take the sensor out (it just unscrews) clean the end that senses the cog on the diff going round and try reconnecting it. The sensor needs to be about 8 thousands of an inch away from the wheel so a bit of trial and error should get it right. Failing that I'd replace the sensor (about £50) as they seem to fail a lot.
FFG
1 off connector (female) 6189-0129
1 off retainer 6918-0322
2 off terminals 1500-0110
2 off wire seals 7165-0135
Web link:
http://swsct.sws.co.jp/index_e.html
I would take the sensor out (it just unscrews) clean the end that senses the cog on the diff going round and try reconnecting it. The sensor needs to be about 8 thousands of an inch away from the wheel so a bit of trial and error should get it right. Failing that I'd replace the sensor (about £50) as they seem to fail a lot.
FFG
ghouly boy said:
I tried supplying 12 volts to the sensor from an external source but again, no result and no speedo.
I'm a bit worried by this bit. I hope you haven't, but I'd have thought you night potentially have damaged the sensor, speedo or worse. I'm thinking 'what if the transducer only produces +/- 3volts' etc.
I'm also a bit worried now you have said this!
I think I'll have another look at it, try cleaning the sensor, connect the wires back up and resetting the ECU. If no joy then I'll have to take it to someone who can hook it up to some diahnostic gear and tell me what is wrong before I wreck anything else.
I think I'll have another look at it, try cleaning the sensor, connect the wires back up and resetting the ECU. If no joy then I'll have to take it to someone who can hook it up to some diahnostic gear and tell me what is wrong before I wreck anything else.
I don't know what sort of sensor it is, but it may well be an MVR sensor in which case it'll only put out a tiny pulse. Sticking 12V onto either side of the connector could well blow either the sensor, or the electronics that drive it, depending which side you connected it to. If the electronics have been fried it's possible for this to affect the ECU, depending how it is connected it may even have caused permanent damage.
Assuming the car basically runs OK, one option to prevent the engine stalling problem while you sort it out is to get the engine warmed up and idling steadily and then unplug the connector to the idle stepper motor. This will give a fixed idle speed. If you still have problems with the engine cutting out then the problem is much more fundamental and probably unrelated to the speed sensor.
Assuming the car basically runs OK, one option to prevent the engine stalling problem while you sort it out is to get the engine warmed up and idling steadily and then unplug the connector to the idle stepper motor. This will give a fixed idle speed. If you still have problems with the engine cutting out then the problem is much more fundamental and probably unrelated to the speed sensor.
I supplied the 12V to the sensor side. Everything else on the car works fine, just the lack of a speedo and now the idling problem.
Is there a way to check if the sensor is still working (i.e I haven't blown it up) without an Osciloscope (not the correct spelling I know) to check the pulses? Or should I just get a new sensor, or even leave well alone and get someone on the case who knows what they are doing?
Is there a way to check if the sensor is still working (i.e I haven't blown it up) without an Osciloscope (not the correct spelling I know) to check the pulses? Or should I just get a new sensor, or even leave well alone and get someone on the case who knows what they are doing?
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