Speedo dropping out

[Chubba]

My speedo only this week, has been playing up.
At start up it will get up to about 20km/h then drop out if it gets going at all. Then when I come to a complete stop it will recover when I move off again. It then may do the same again till I stop or it will stay on working fine for the rest of the drive. Do I have a mechanical cable link or is there an electrical sender?
Any thoughts.

[garett]

i had a similar issue ... turned out to be my dash cluster... ended up with a multimeter to test the signal at the dash. managed to get a petrol cluster then swapped the speedo section into my diesel cluster. works a treat.
i suggest you try that if you dont have a signal then most likely the sender ( pull it out test with mulitmeter spinning with your fingers should be quick enough to get a signal)

[mudnut]

Pull the sender off the gear box, (Is on the top Drivers side on a Q so should be there for a U.) Turn the ignition on and get someone to watch the speedo as you rotate the drive shaft. Alternatively, use the shaft or get a 3/32 or 2mm square drive and use your battery drill to run the speedo drive. My hitachi 12 volt drill runs the speedo at around 60kph.

[mudnut]

While using your fingers to twist/flick the drive you should see about 2-3 volts momentarily on AC volts on your meter.

To make it a lot easier to attach the alligator clips, I used a knife to strip a little section of both wires to connect the multimeter and will use a bit of silicon to seal them properly.

With the drill, I get around 5.5-6 volts.

[mudnut]

On a GQ cluster, the connecting screws for the speedo are easy to get to. You can use the battery drill or have the rear wheels raised and the front wheels chocked, transfer case in 2wd, etc to run the speedo and check the voltages there. Not sure on a GU though as I have not seen one yet.

[Yendor]

Do you have a scan tool? I think the ECUTalk works with the 4.5. Does the speed reading also drop out?

What about factory cruise control? does that drop out when speedo drops out?

[Chubba]

Do you have a scan tool? I think the ECUTalk works with the 4.5. Does the speed reading also drop out?

What about factory cruise control? does that drop out when speedo drops out?

No scan tool.
What do you mean "speed reading"?
Factory cruise control does not work when speedo has dropped out.

[Yendor]

No scan tool.
What do you mean "speed reading"?
Factory cruise control does not work when speedo has dropped out.
Speed reading shown on the scan tool....

[Chubba]

Ok. Have been trying to think this one through and thinking hurts me but.
The vehicle speed sensor sends a signal to the speedo and odometer, is it also used to help operate the auto trans gear changes. If the vss was not working properly should I see abnormal auto trans operations? At the moment the trans is still running perfectly. So would that suggest a problem with the dash cluster instead of the vss? Just trying to work out where to start looking before I pull something apart a stuff it when that wasn't the problem.

[Kimbo63]

[QUOTE=mudnut;676094]While using your fingers to twist/flick the drive you should see about 2-3 volts momentarily on AC volts on your meter.

To make it a lot easier to attach the alligator clips, I used a knife to strip a little section of both wires to connect the multimeter and will use a bit of silicon to seal them properly.

Hey mudnut that is not good practice cutting insulation of your wires it can and will cause green death get yourself some multimeter probe spoons cheap as chips saves a lot of hassles down the track 67374

These just slip in the back of the plug
:-) zzzzzzzzzzzzz

[Yendor]

The VSS sends the signal to the instrument computer mounted in the instrument cluster. From here the signal is sent to the engine computer, auto computer and cruise control computer.

It's strange that the cruise control stops working but the auto shift isn't affected. It might be a problem with the instrument computer. Were you able to check the vehicle speed via a scan tool?

[mudnut]

[QUOTE=mudnut;676094]While using your fingers to twist/flick the drive you should see about 2-3 volts momentarily on AC volts on your meter.

To make it a lot easier to attach the alligator clips, I used a knife to strip a little section of both wires to connect the multimeter and will use a bit of silicon to seal them properly.

Hey mudnut that is not good practice cutting insulation of your wires it can and will cause green death get yourself some multimeter probe spoons cheap as chips saves a lot of hassles down the track 67374

These just slip in the back of the plug
:-) zzzzzzzzzzzzz

Yep, have some, but most blokes don't have them. The silicon will stop any ingress of moisture if pressed into the gap.

[Chubba]

The VSS sends the signal to the instrument computer mounted in the instrument cluster. From here the signal is sent to the engine computer, auto computer and cruise control computer.

It's strange that the cruise control stops working but the auto shift isn't affected. It might be a problem with the instrument computer. Were you able to check the vehicle speed via a scan tool?

No mate. Don't have one.
Would you say that the problem probably is in the instrument cluster?

[Yendor]

No mate. Don't have one.
Would you say that the problem probably is in the instrument cluster?

Yeah that would be my guess. Probably not the gauge but the instrument ECU.

It sounds like the VSS is working.