Technical speedometer reads zero and power steering light on, this started as erratic speedometer about 4 years ago,tried just about everything, HELP !

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Technical speedometer reads zero and power steering light on, this started as erratic speedometer about 4 years ago,tried just about everything, HELP !

davesmailslot

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2008 PANDA. Speedometer reads zero and power steering light on, this started about 4 years ago as an erratic speedometer.Have spent a shed load on diagnostics etc. latest suggested ABS control module as signal sent from same gave a speedometer, reading,swapped out ABS unit and still exactly the same problem, so it seems to be a problem prior to ABS unit ?
 
Presumably, you have checked the system voltage is holding up? Battery faults cause odd things to happen but (again), I expect you've swapped the battery. Alternator can appear ok but if that struggles to give enough charge, similar things happen (I had that issue with a 2007 1.2).

My suspicion is a body computer issue (bad connection, cracked track in the circuit board, etc). A wild guess, so see what the fault codes show.

You need to get the fault code data. With something this deep a proper diagnostic setup is needed. MultiECUscan is about £50 then you'll need an OBD2 connection set.

MultiECUscan runs on any PC, even an old Windows XP does the job. I have a connection set like this https://www.ebay.co.uk/itm/153448656839?hash=item23ba40afc7:g:AcsAAOSwVFlT4TvM
 
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Speedo gets it signal indirectly from a front ABS sensor (100% sure it’s a front sensor)

I believe it’s the front left (90%)


The easiest thing to do is to connect a scan tool that can access the ABS module

Log the live data from the 4 sensors while driving down a straight road and see if all 4 are the same


Power steering is proportional to road speed. If it’s not getting the correct data it will throw an error code

It’s highly likely to just be a simple ABS sensor, wheel bearing or wiring damage considering it’s been intermittent for years
 
The last tests,earlier this year,did show all ABS sensors fine and signal generated from ABS unit gave response at speedometer.The conclusion was ABS module at fault.I have plugged in a spare ABS module but fault still exactly the same ( not sure if old problem should be cleared first )
My feeling is that fault could be prior to ABS module, possibly a bad earth or open or short circuit ?. In order to eliminate voltage problem I have just turned key to first position with a battery charger connected to battery and power steering light still remained on.
 
Does the abs actually work? If you slam on the brakes on a wet day does the pedal starts pulsating? this would tell you if the ABS computer know's that the car is at speed and that there is a difference between wheel speed left and right? If you have checked that part then you need to go further up.

I suggest that you find a wiring harnass schematic and see if you can borrow or buy a scope and start probing wires.
 
Does the abs actually work? If you slam on the brakes on a wet day does the pedal starts pulsating? this would tell you if the ABS computer know's that the car is at speed and that there is a difference between wheel speed left and right? If you have checked that part then you need to go further up.

I suggest that you find a wiring harnass schematic and see if you can borrow or buy a scope and start probing wires.
The (spare) ABS I have fitted now is just resting on top of original and plugged in but I have left all brake pipes etc connected to original ABS so the ABS system will not activate in event of a skid.
 
Activate the speedometer via software I used WOW but others will work

Here’s mine

If this test fails the fault is between the body computer and dash

If it passes these two parts are eliminated


 
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Thanks all for help so far, Koalar, I have no way of sending a signal to activate speedometer but perhaps I could pay for this at an Auto electrics station but earlier this year a garage used a signal generator to ensure speedo was capable of responding to a signal, I assume from ABS unit.
 
Being able to test things for yourself at home make life so much simpler. Everything the garage can do can be done for less than £50 in cables or multiplexer and a windows laptop

Without we are often shooting blind

Does your car have rear parking sensors ?

Most electronic control units either work or don’t, it’s rare they are intermittent especially for 4 years

A chafing wire, corrosion on connector and such like are more likely in my opinion

Front ABS sensor as been known to cause erratic speedo reading as have an overheating wheel bearing
 
Being able to test things for yourself at home make life so much simpler. Everything the garage can do can be done for less than £50 in cables or multiplexer and a windows laptop

Without we are often shooting blind

Does your car have rear parking sensors ?

Most electronic control units either work or don’t, it’s rare they are intermittent especially for 4 years

A chafing wire, corrosion on connector and such like are more likely in my opinion

Front ABS sensor as been known to cause erratic speedo reading as have an overheating wheel bearing
Thanks for help, no rear parking sensors and I think your right the most likely cause would be O.C. or S.C. somewhere
 
The (spare) ABS I have fitted now is just resting on top of original and plugged in but I have left all brake pipes etc connected to original ABS so the ABS system will not activate in event of a skid.
Would be very dangerous to drive on the road like this

As well as the ABS the module is also used for the Electronic Brake Force Distribution

Without it if you slam on the brakes the rears will lock up first and the car will try and swap ends uncontrollably.
 
Without it if you slam on the brakes the rears will lock up first and the car will try and swap ends uncontrollably.
I had a failed rear caliper on the 100HP. Sudden braking had the back-end swing around. I was able to catch it but very scary. A new caliper fixed the problem - fluid leak from hand brake shaft seal had contaminated the brake. There was no warning from the ABS which is odd because the working brake had locked its wheel, the imbalance threw the back end sideways. It's possible there was an ABS light during the event that I didn't see (too busy!!!) but I suspect nothing appeared on the dash.

My point is that ABS does not necessarily throw out faults even when there are serious problems going on.
 
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