Speedo not working
Discussion
This is what you your looking for (the red connector)
The 3 bullet connectors at the bottom go into the thick grey cable you can see and go to the speedo. The other end of the connector goes into the wiring loom and if anything like mine there is no play in the length, but there is plenty of extra length on the cables from the speedo.
I've had a dodgy speedo for 2 years now, sometimes works, but mainly doesn't. Tried a new sender, this just altered the way that it didn't work. Original problem was it didn't work at startup but after a while it would then work. The replacement sender did the opposite, the speedo would work for a while and then stop. Tried a different speedo (supplied via Gerald-tvr) but the same happened.
I was going to have a go at the connector, but with it being so tight I'm not sure what I'm going to do.
The 3 bullet connectors at the bottom go into the thick grey cable you can see and go to the speedo. The other end of the connector goes into the wiring loom and if anything like mine there is no play in the length, but there is plenty of extra length on the cables from the speedo.
I've had a dodgy speedo for 2 years now, sometimes works, but mainly doesn't. Tried a new sender, this just altered the way that it didn't work. Original problem was it didn't work at startup but after a while it would then work. The replacement sender did the opposite, the speedo would work for a while and then stop. Tried a different speedo (supplied via Gerald-tvr) but the same happened.
I was going to have a go at the connector, but with it being so tight I'm not sure what I'm going to do.
Well I haven't had chance to drop the steering column yet but fumbling around behind the dash pulled out 2 red connectors which look like they might fit together. The one going to the grey cable looks like the female and just has a red and black wire with the cable screen going to the 3rd pin. The other one is a male and looks to have 2 sets of wires connected to it - could this be one from the sensor and the other to the ECU?
Is it too much of a coincidence that these 2 connectors match - in other words they do match and there'll be no mushroom cloud if I connect them together?
Is it too much of a coincidence that these 2 connectors match - in other words they do match and there'll be no mushroom cloud if I connect them together?
Yes thats it - there are 3 wires, +12v, Gnd & signal.
I have done a bit of experimentation with a speedo courtesy of Norman (Gerald-TVR)
The signal from the sensor to the speedo is a 12v square wave (on/off signal).
If you get your car in the situation where it will roll slightly if you take your foot off the brake - then put a voltmeter across the gnd and signal pins. Allow the car to roll very slowly with the ignition on and the signal should alternate between 12v and diddly squat on the volt meter. If it does (and I'm pretty sure it will) then your sender is fine and your speedo is faulty.
You don't need the engine running or it in gear - and it can roll forwards or backwards. Just don't do it on a steep incline as you won't have servo assistance on the brakes when you've pumped the pedal a few times.
Chris
I have done a bit of experimentation with a speedo courtesy of Norman (Gerald-TVR)
The signal from the sensor to the speedo is a 12v square wave (on/off signal).
If you get your car in the situation where it will roll slightly if you take your foot off the brake - then put a voltmeter across the gnd and signal pins. Allow the car to roll very slowly with the ignition on and the signal should alternate between 12v and diddly squat on the volt meter. If it does (and I'm pretty sure it will) then your sender is fine and your speedo is faulty.
You don't need the engine running or it in gear - and it can roll forwards or backwards. Just don't do it on a steep incline as you won't have servo assistance on the brakes when you've pumped the pedal a few times.
Chris
Thanks Chris - but the connectors weren't connected - I just found them loose on different sides of the steering column tucked into different parts of the other wires.
I can check for the sensor signal as you suggest but since they were already disconnected then this is likely the reason for it not working (unless previous owner disconnected it whilst tracing the fault!).
Am I likely to cause any damage by connecting them together? Can it be that they are completely unrelated?
Graham
I can check for the sensor signal as you suggest but since they were already disconnected then this is likely the reason for it not working (unless previous owner disconnected it whilst tracing the fault!).
Am I likely to cause any damage by connecting them together? Can it be that they are completely unrelated?
Graham
53,000 which I guess should be taken with a pinch of salt given that the speedo probably hasn't been connected for a while!
From the state of the driver's seat I would suggest at least 20 to 30k more.
I'll give it a go tomorrow evening then - I guess if the connectors fit together not much can go wrong
From the state of the driver's seat I would suggest at least 20 to 30k more.
I'll give it a go tomorrow evening then - I guess if the connectors fit together not much can go wrong
FLW ..........OK - so no mushroom cloud after connecting the two red connectors together and the speedo pointer moves but seems to act more like a rev counter!
Hard to describe how it behaves but it does seem to rise and fall with the engine revs rather than the road speed. The odometer increased by around 6 miles on the test drive which is a bit more than expected but not very scientific.
Maybe that's why it was disconnected in the first place 'cos the miles were going up faster than actual!
Any thoughts on whether this is likely to be the sensor or the speedo?
Hard to describe how it behaves but it does seem to rise and fall with the engine revs rather than the road speed. The odometer increased by around 6 miles on the test drive which is a bit more than expected but not very scientific.
Maybe that's why it was disconnected in the first place 'cos the miles were going up faster than actual!
Any thoughts on whether this is likely to be the sensor or the speedo?
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