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Discussion Starter · #1 ·
I have searched related threads on the forum but still have not found the answer.
Just bought a 2002 1.2 Comfort with a non working Speedo / Odometer which I would ideally like to fix.
Had a look this afternoon.
Took the front wheels off & put on axle stands to save countless test drives up the road.
The warning light with the key symbol is permanently on, Speedo & odometer dead, all other gauges/ lights work fine.
Getting a P0500 fault code (via the dash warning lights flashing).
Had a visual check of abs ring & sensor and both look clean and secure.checked for blown fuses, none.
Checked wiring of non original cd radio & found it has correct wiring plugs for loom (ie not bodged in)
Took the instrument panel out & checked the connector, looked okay
I did this with the battery disconnected, when I reconnected it the Speedo & Odometer worked perfectly (on axle stands)
Put wheels back on went for test drive - dead again & half a mile in the warning light came back on ��
So I know the Speedo works & it appears the abs sensor works so I’m stuck & can’t figure out why it worked perfectly whilst on axle stands but not when actually on the road.

 

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I did reply to your welcome post, but will add to that, now we have more in depth information.

That sounds weird that it works when there is no load on the drivetrain, it's almost like the old school Speedo drive failure ??

Is there any play in the wheel bearings?

Can you see any wear on the sensors( the tip nearest the pick up rings can break or wear to metal (it would bring the EML on, with a code for the sensor though)

Have a look at the ECU and BCM wiring connections for corrosion or water damage, also check the BCM lid seal for cracks too

I'm still learning with Corsa's having been around cars for a while I'm more used to classic minis ?
 

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Pedal test you got the code?

Got op-com?

P0500 is speed sensor checked all wiring for splits etc?

Spanner light constant flashing tends to be immobiliser related

Tried clearing the code?


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Is it ABS or non-ABS? they use different systems for the speedo.

It could be a fault on the clocks, the connector at the back is known for coming loose.
 

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Discussion Starter · #5 ·
I did reply to your welcome post, but will add to that, now we have more in depth information.

That sounds weird that it works when there is no load on the drivetrain, it's almost like the old school Speedo drive failure ����

Is there any play in the wheel bearings? Haven’t checked

Can you see any wear on the sensors( the tip nearest the pick up rings can break or wear to metal (it would bring the EML on, with a code for the sensor though) Didn’t take it off tbh

Have a look at the ECU and BCM wiring connections for corrosion or water damage, also check the BCM lid seal for cracks too. This will probably be next place to look

I'm still learning with Corsa's having been around cars for a while I'm more used to classic minis ��
The weird thing is when on axle stands it worked perfectly, as I went through the gears the speed rose accordingly & odometer was registering distance traveled as well. 5 mins later with wheels on & not working again.
 

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This does sound like an electrical fault, have you checked the connection under the wheel arch liners for the sensors? The seals do occasionally fail allowing water in.

My goal is to do all the free fault diagnosis and repairs as we can before you have to spend any money
 

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And another freebie is vexorg's suggestion (this was on my mind and, for once, I might not be dead flat wrong). Fine up on axle stands, but bumps and humps burgers up the clocks connector again. I suspect the same at least contributes to my aircon's failings.
 

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Discussion Starter · #8 ·
Is it ABS or non-ABS? they use different systems for the speedo.

It could be a fault on the clocks, the connector at the back is known for coming loose.

I had the instrument panel out & was able to drive up the road whilst applying pressure to the connector & it made no difference, not even an occasional Speedo needle movement. The only time it worked was after the battery had been disconnected & reconnected & the car was on stands. I had it like this for a couple of hours whilst I did other jobs & repeatedly started it & tested it running through the gears & the Speedo read perfectly - so I thought I had fixed it. Gently eased it back down on to its wheels & it was not working instantly - as I went up the road it didn’t start off working & then stop , it was dead as soon as I set off.
 

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Discussion Starter · #9 ·
And another freebie is vexorg's suggestion (this was on my mind and, for once, I might not be dead flat wrong). Fine up on axle stands, but bumps and humps burgers up the clocks connector again. I suspect the same at least contributes to my aircon's failings.

Thanks, See my reply to Vexorg
 

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Discussion Starter · #10 ·
This does sound like an electrical fault, have you checked the connection under the wheel arch liners for the sensors? The seals do occasionally fail allowing water in.

My goal is to do all the free fault diagnosis and repairs as we can before you have to spend any money
Me too! The car was less than £300 so I’m hoping to repair it for pennies.
As it worked for a few hours on stands but failed the second I set off on the road I am wondering about voltage stability or an ecu fault?
 

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Discussion Starter · #11 ·
PUGH125K , cant seem to reply to your post.

Yes, got the code from doing pedal test.
No, i havent got op-com
Checked speed sensor wiring (although have not removed it). Speedo was working fine whilst on axle stands with front hubs spinning in gear
Spanner light is static/constant (only flashes when checking for fault codes)
Spanner light goes out if you disconnect/reconnect the battery. I dont know how else to reset codes.
Thanks
 

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Personally I'd try checking all the wiring connections for the speed sensors, the ones under the wheel arch liners and at the ECU end. Then check the BCM and ECU for signs of water getting around them.

The only other way to reset codes is to connect the OBD reader
 

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Discussion Starter · #13 ·
Update.
Decided to change engine oil & filter today and as the sump plug is at the back of the sump I used the opportunity to put the car on stands again.
I took the nsf speed/abs sensor off, checked the wiring, cleaned it up & gave it a squirt of WD40 & reassembled. Took off & checked the ECU terminals. Reconnected battery.
Started car - Speedo & odometer worked perfectly whilst on stands. Put wheels back on, set off on test drive- no Speedo.
It didn’t start working then stop, it didn’t work from the moment I turned a wheel. After half a mile of no Speedo it triggers a P0500 speed sensor fault code.
Back into driveway, disconnected & reconnected the battery to clear the fault code. Jacked up car (left the wheels on this time)Started car, into gear - Speedo works perfectly again . Lowered it down very gently, set off - no Speedo ��
So something is causing it to not work when under load. The Speedo & speed sensor seem fine.
Help!
 
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