When my l322 td6 was killing an abs sensor i could get upto about 10mph then upto 70 before it would register a change in speed it was delayed and laggy more so when wet, they send speed from rear left sensor through the abs pump to the cluster,
I dont know how the p38 prosses wheel speed to the speedometer though im afraid, if you could get diagnostics on all 4 corners and see they read the same,
Possible a wheelbearings got play and upsetting the relucter ring reading,

iirc the ABS module counts how many teeth on each reluctor ring pass per second and average it across the 4 wheels. I cannot remember how many pulses there are but Wammers put it up a few times. That rate goes to the BECM and a signal is sent to the speedo to display the current speed. On the back of the speedo are a couple of pots that calibrate that signal so it lines up with the marks on the speedo.
 
iirc the ABS module counts how many teeth on each reluctor ring pass per second and average it across the 4 wheels. I cannot remember how many pulses there are but Wammers put it up a few times. That rate goes to the BECM and a signal is sent to the speedo to display the current speed. On the back of the speedo are a couple of pots that calibrate that signal so it lines up with the marks on the speedo.
Since the cruise control and eas auto raise/ lower work correctly I'm thinking the sensors and feed to becm are good and the issue is between becm and speedo.
Pots on the back seem likely, there is also an occasional tick/ clunk in the console although that doesn't mostly seem to link to any speedo action.
I think first will be, when weather reasonable, to clean all the plugs and pins on that circuit connection from the becm. Then move on to the console afterwards. Chase any issue closer to the instruments one stage at a time.
 
From RAVE:

Speedometer
The signal to activate the gauge is originated at the
ABS wheel sensors, transmitted to the ABS ECU
(Z108) which then puts out a usable signal to the
Instrument Cluster (Z142) of 8000 pulses per mile or
4972 pulses per kilometer. The signal is also
transmitted to other ECU’s, such as the Engine
Control Module (ECM) (Z132) and the Cruise Control
ECU (Z121).
 
Since the cruise control and eas auto raise/ lower work correctly I'm thinking the sensors and feed to becm are good and the issue is between becm and speedo.
Pots on the back seem likely, there is also an occasional tick/ clunk in the console although that doesn't mostly seem to link to any speedo action.
I think first will be, when weather reasonable, to clean all the plugs and pins on that circuit connection from the becm. Then move on to the console afterwards. Chase any issue closer to the instruments one stage at a time.

Tick noise is usually associated with TC light coming on.
 
I was going to send cake ,But you need candles for a birthday cake and when i got the postage price for all those candles:eek: I though bugr that n ate the cake :oops: Dont tell ,@,Dopey...:D:D
Your secret's safe with me dubbleRR!
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...CAKE:cool:
 
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Tick noise is usually associated with TC light coming on.
Never seen the TC light on as far as I recall.

Usually seems to be some time after setting off, longer if he is cold / damp, sometimes not at all if he is warm / dry. Occasionally the speedo doesn't work until after the tick, but that is rarer and the two don't happen together. I'd assumed it was a sign of something damp / sticky / god knows what behind the cluster.

Now we seem to have good EAS I can start moving to other issues. He's now been parked up for 48 hours+ on extended height with the relay pulled and no sign of him dropping at all now. So it has sorted the leaks OK. Previously he'd have been high at the front where those bags were done but on the stops at the rear. I suppose after all the abuse they have had I ought to add replacing all the bumpstops to the task list....
 
You can sort this mate, have you managed to source one?
What's happened to the existing airbag? :)

On the fourth try I found a garage that would let me buy a replacement air spring and have it shipped to their shop. The owner was a bit leery about installing it but he did a bit of online checking and decided it was not that much different than some American cars so he thinks he can acomodate me. Starting to feel a little less depressed. Might be fixed by Saturday.
 
Never seen the TC light on as far as I recall.

Usually seems to be some time after setting off, longer if he is cold / damp, sometimes not at all if he is warm / dry. Occasionally the speedo doesn't work until after the tick, but that is rarer and the two don't happen together. I'd assumed it was a sign of something damp / sticky / god knows what behind the cluster.

Now we seem to have good EAS I can start moving to other issues. He's now been parked up for 48 hours+ on extended height with the relay pulled and no sign of him dropping at all now. So it has sorted the leaks OK. Previously he'd have been high at the front where those bags were done but on the stops at the rear. I suppose after all the abuse they have had I ought to add replacing all the bumpstops to the task list....

Bump-stops are pretty robust. I'd leave well alone unless they're hanging off.

Sounds like there's something going on with your cluster, possibly dodgy connection. Beware any yellow cables or plugs as that will be the airbags. Other than that, have a good wiggle!
 
fidget with the cable connectors too :eek:

Struggling to get back into the work-stride?

Not at 12th night yet so I am playing Christmas songs on my phone and finishing the scraps. All bikkies now gone but some chocolates and cake left. All coffee being drunk with double-cream or brandy-cream! Tried some Baileys last night but I don't think my stomach or liver can take much more. Discovered a very nasty bruise on my side last night that together with the cuts on my hand on New Year's Day lead me to believe I must have fallen or crashed through something on my way back from the New Year's Eve party. God knows what happened but I hope I didn't damage anything!
 
Struggling to get back into the work-stride?

Not at 12th night yet so I am playing Christmas songs on my phone and finishing the scraps. All bikkies now gone but some chocolates and cake left. All coffee being drunk with double-cream or brandy-cream! Tried some Baileys last night but I don't think my stomach or liver can take much more. Discovered a very nasty bruise on my side last night that together with the cuts on my hand on New Year's Day lead me to believe I must have fallen or crashed through something on my way back from the New Year's Eve party. God knows what happened but I hope I didn't damage anything!
marinade the stale cake in some of the chocolate.. with some added baileys
 

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