Speedo not working!
Discussion
Humm, let me think "Officer" - How fast was I going? I don't actually know my speedo has failed and I was in a GPS black spot.....
Thankfully not reality, but could very well be as my speedo really has stopped working. Can anyone offer advice as to how to diagnose which bit is the issue (gear box sender, impossible to reach connector block in transmission tunnel, wiring from connector block (I'm not 100% sure of the thick grey wire as have had to snip and solder back together and it seems to be a shielded wire with a thin red inner core?) or the speedo in the dash.
Before I pull out the dash again (didn’t find any loose wires in my previous foray behind it), I welcome any advice the forum may offer.
Thanks
WhiteS3
Thankfully not reality, but could very well be as my speedo really has stopped working. Can anyone offer advice as to how to diagnose which bit is the issue (gear box sender, impossible to reach connector block in transmission tunnel, wiring from connector block (I'm not 100% sure of the thick grey wire as have had to snip and solder back together and it seems to be a shielded wire with a thin red inner core?) or the speedo in the dash.
Before I pull out the dash again (didn’t find any loose wires in my previous foray behind it), I welcome any advice the forum may offer.
Thanks
WhiteS3
If I were you, I would start with the sender connector.
). I had the same problem on my S3C. I don't remember exactly how I did, it was 3 years ago, but I removed the sensor from the gearbox to check and clean the connector. After that, the speedo was working one's again.
If the connector is OK, I would check the sensor himself :
https://www.youtube.com/watch?v=G1XzwZE6n8M&ab...
If the sensor is OK, I would check the wires, and at the very last moment, the speedo.
White S3 said:
(gear box sender, impossible to reach connector block in transmission tunnel,
It is not impossible (Impossible isn't French ). I had the same problem on my S3C. I don't remember exactly how I did, it was 3 years ago, but I removed the sensor from the gearbox to check and clean the connector. After that, the speedo was working one's again.If the connector is OK, I would check the sensor himself :
https://www.youtube.com/watch?v=G1XzwZE6n8M&ab...
If the sensor is OK, I would check the wires, and at the very last moment, the speedo.
Fefeu,
Thanks I'll start there. Will try to do it with the sender in situe and connect a voltage feed via the connector in the (impossible to reach) transmission tunnel and jack up the rear end to allow the wheels to rotate. Not sure how to test the continuity of the wiring from the connector to the speedo without removing the speedo or replace the contacts themselves in the limited space.
Any other sage words of advice from the community - I know there have been a few speedo issues out there in the S-Community but cannot find any of the threads.
Thanks I'll start there. Will try to do it with the sender in situe and connect a voltage feed via the connector in the (impossible to reach) transmission tunnel and jack up the rear end to allow the wheels to rotate. Not sure how to test the continuity of the wiring from the connector to the speedo without removing the speedo or replace the contacts themselves in the limited space.
Any other sage words of advice from the community - I know there have been a few speedo issues out there in the S-Community but cannot find any of the threads.
Output from the sender is a 5V square wave, with frequency following the rotational speed.
You'll need a frequency measuring device to make any sense of it: I have a Hantek digital oscilloscope module that works with a laptop, cost about £30 on eBay. Its too slow for 'electronics' work, but at automotive frequencies it's fine. I've looked at fuel injection and ignition pulses with it as well, and it convinces me that things are doing what they ought to.
All this is easier and safer with the sender out of the gearbox and spun by hand!
Can't see why you can't access the wiring connector: mine is on top of the gearbox, near the gear lever hole.
You'll need a frequency measuring device to make any sense of it: I have a Hantek digital oscilloscope module that works with a laptop, cost about £30 on eBay. Its too slow for 'electronics' work, but at automotive frequencies it's fine. I've looked at fuel injection and ignition pulses with it as well, and it convinces me that things are doing what they ought to.
All this is easier and safer with the sender out of the gearbox and spun by hand!
Can't see why you can't access the wiring connector: mine is on top of the gearbox, near the gear lever hole.
Edited by mentall on Monday 12th April 12:55
Mentall
Thanks. My sender is on the side of the GB level with the gearstick and the wiring (sender to connector block is approx 5cm so need two hands down through the hole just to fingertip hole the connector block! You have to love Blackpool engineering. It was only possible to reach with full exhaust off to reconnect during body of chassis resto 10yrs ago when I had a pit. Doubt I could get the sensor out without getting it up on ramp.
Found an old post re second connector near steering column so will check that too.
Thanks. My sender is on the side of the GB level with the gearstick and the wiring (sender to connector block is approx 5cm so need two hands down through the hole just to fingertip hole the connector block! You have to love Blackpool engineering. It was only possible to reach with full exhaust off to reconnect during body of chassis resto 10yrs ago when I had a pit. Doubt I could get the sensor out without getting it up on ramp.
Found an old post re second connector near steering column so will check that too.
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