Earthing Straps

I took the GTA out of hibernation last week and did a fairly rapid 30 mile run to see that everything was as it had been when it went into the garage in November only to find that the speedo is now completely dead.
I've checked and cleaned the earth that attaches to the n/s front suspension turret adjacent to the battery. The earth that runs from the n/s bank cylinder head to the rear bulkhead and also taken apart/ cleaned and silicone greased (DC4) the multi-plug situated behind the o/s rear wheel. Are there more earthing straps to check and if so could someone tell me where to search?
Looking through my workshop manual (MR273) I cannot see any reference to any earthing points and no general wiring diagram.
Any suggestions would be very welcome.

Murf.

My atmo speedo is lazy until the battery is fully charged...Try a good charge...
It sounds like you have done the obvious stuff...The servisol contact cleaner and making sure the pins are pushed home can work for some...
My turbo speedo responded to voodoo and a sacrificial offering conducted at RATS...after all other endeavours failed.

........... and also taken apart/ cleaned and silicone greased (DC4) the multi-plug situated behind the o/s rear wheel. Are there more earthing straps to check and if so could someone tell me where to search?

By "multi plug" can I assume you mean the 3pin connector with the green rubber waterproofing "O" rings ? ......... This must always be the first port of call for speedo failures.

It is also unlikely to be an earth if all the other instrument functions are working correctly.

Everything else that normally works is working so I'll have another fiddle with the 3-pin connector behind the rear wheel arch tomorrow, weather permitting.

Finally got the car jacked up this afternoon and had another look at the three pin connector behind the wheel arch but the terminals all look good and clean and it seems to snap together properly. I sprayed wd40/ re-assembled it and went for a drive but still nothing from the speedo.
I think the voodoo solution is beckoning!
It has occurred to me that the problem might be similar to the one John C had with the odometer rotors partially seized in that my odometer is reading 080051 and I wonder if it struggled at the change from 79 to 80000. Another avenue I have not yet pursued is the 'not properly seated sensor' that turbell found was causing his speedo malfunction. I'll have to book some ramp time with my friendly garage to investigate that. Could someone point me towards where the sensor is located?

Murf

........... Could someone point me towards where the sensor is located?

If you follow the cable form back from the 3 pin connector, it will take you to the sensor alongside the off side driveshaft where it enters the gearbox.

If all is OK there, there are other connectors that will need checking and cleaning, but it will be necessary to remove the steering wheel and the binnacle over the instrument unit.
The large connector on the LHS of the instruments, and the two connectors that plug into the speedo circuit board on the RHS of the instruments.
Let us know how you get on.

Assuming the connector you have cleaned has the 3 pins in a line, follow it up towards the bulkhead and on my car (an early 86 Turbo model) there is a round 3 pin connector just by the stainless shield. Perhaps this needs a clean too. I seem to remember that you need to pinch it to release it. Being by the exhaust manifold, I expect it gets quite hot too.

Agree with the advice above.

For some reason switching the rear demister on and off whilst driving can bring the speedo back to life.

Check that the 3 pins in the connector block are making good contact. They're tricky to bend to make a tighter fit but that can help make sure they make best contact.
I also found that in addition to cleaning the 3-pin connector block in the rear wing spraying it with something like "Damp Start" (once you've connected it back up!) protects that connection from water etc.

All this does assume that the problem is at the engine-bay end of things but it's pretty easy to access and check, so makes a good starting point

I've followed the various suggestions and checked the seating of the sensor where it locates in the side of the gearbox. It seems to be positioned correctly although I would have liked to inspect it more closely on a ramp. Sadly despite my pleading the garage are booked solid so I was only able to get to it with the car jacked/wheel removed.
The local Renault dealer has assured me that although the sensor still shows on their database it is no longer available so I'm not sure where to go from here.
I'd hoped to swap out the existing one with a replacement before tackling the daunting prospect of disturbing the instrument cluster wiring. My previous experience of delving behind dashboards is making me very nervous about that prospect. If anyone has a spare s/h one or knows of an aftermarket equivalent then please let me know.

Murf.

[mettersl]

Simon auto have the senders if you need them, but sit down when you check the cost.

If the speedo was working before you laid the Alp up, the chances that the sensor has failed all by itself over that period is very remote. It is more likely that a connection has gone high resistance in a connector to the instrument unit.
Having cleaned and checked the most common cause of failure ... the 3 pin on in the engine bay ... I am afraid you will have to bite the bullet and get to the instruments and start checking there.
If you want to check the sensor to make sure that it has not gone open circuit, before you attack the instrument unit, disconnect the 3 pin connector and with a DVM switched to resistance, you should find on two of the pins a resistance of around 2.1 ohms. Either of those pins to the third pin should show open circuit. Also check that the sensor has still got the two fingered locking clip still in place with a small bolt to the gearbox housing via a spacer. If all that checks out, then I would not worry about a faulty sensor ....... It is a passive component with no moving parts which give very little trouble, except maybe where the wire enters the sensor hence the resistance check.
I hope this helps.

John

I am totally useless at electrics but having just had to sort out my 610 wireing looms in the back, I didn't but the Sparky did we did come across the wiring each side of the demister the plastic had deteriorated because of UV and the wire was exposed just a thought might be shorting out, the chaps above are the kings at this stuff.

Just to update on the situation, I've coerced my garage into putting the car on a ramp on Saturday to at least rule out/test the gearbox mounted sensor using John C's very helpful info on what the readings on the meter should be.
Assuming that it proves to be functional then I'm going to nervously tackle the connectors inside the instrument binnacle using the brilliant step by step guide set out in 'speedo fix 2'. This may have to wait for a week or two but I'll post on any progress.
Many thanks to everyone for the responses to this issue.

Murf

........ I'm going to nervously tackle the connectors inside the instrument binnacle

If you have not removed the steering Wheel before, you will need a couple of 7 mm set screws and a 5 mm Allen Key. The set screws need to have about 40 MM of thread.
See link below to Halfords who have them ..... though the nuts are not required.

http://www.halfords.com/workshop-tools/ ... 0mm-hfx692

John

Or "borrow" one of the bolts that holds the engine rocker covers on.
Saves a trip to Hell-Frauds and £2.09