Speedo not working, but no ABS light!

Savestones · 20th December 2023, 07:13

In this sea of ABS issues I have an interesting fault on my car. The speedo will not work reliably, sometimes coming back to life for a bit only to fall back to 0 km/h again after the first (smooth or sharp) bump in the road or hard braking action. Now it's mostly stuck at 0 km/h.

The right front wheel bearing has play, so the symptoms are not completely unexpected. However, the funny thing is is that the ABS light does not stay on. So far, in ~200 kms it has popped on 3 times for less than 2 seconds each time. Also, braking seems normal enough.

I'm confident that swapping out the wheel bearing will resolve the issue I'm experiencing, but could anyone shed some light on the combination of faulty speedo without an ABS light? As far as I understand my ABS light should be on, and I'd love to understand the ABS system on these cars a bit better

Mike Noc · 20th December 2023, 08:25

Unplug one of the ABS sensors and turn key to position II - does the ABS light stay on? If not Mr Previous Owner may have bodged it due to another problem - not unknown for it to be wired into another LED on the IPK display.

planenut · 20th December 2023, 08:56

As I understood, a faulty o/s/f abs sensor could affect the signals to the speedo and the fuel gauge.

Good luck with it, but fear not, someone with more knowledge and more advice
will be along soon.

Have a read through this thread.
https://www.the75andztclub.co.uk/for...d.php?t=326201

Savestones · 20th December 2023, 09:43

Quote:

Originally Posted by Mike Noc

Unplug one of the ABS sensors and turn key to position II - does the ABS light stay on? If not Mr Previous Owner may have bodged it due to another problem - not unknown for it to be wired into another LED on the IPK display.

That's going to be my next step, thanks! Sometimes I get hung up on 1 known fault, and I forget multiple things can be wrong/broken at the same time hahaha

Savestones · 20th December 2023, 15:36

Quote:

Originally Posted by Mike Noc

Unplug one of the ABS sensors and turn key to position II - does the ABS light stay on? If not Mr Previous Owner may have bodged it due to another problem - not unknown for it to be wired into another LED on the IPK display.

So, got around to this. With the plug fully disconnected, the ABS light stays illuminated. Also noticed that the plastic retainer clip on the 'car side' abs connector has broken off, and the plug wasn't fully connected. However, disconnecting and reconnecting the plug only resulted in the speedo now fully not working and the ABS light popping up more often. Also noticed that when I brake in the short periods the ABS light is on, the ABS will kick in immediately. Also noticed that the fuel gauge is acting strangly (unless someone if fueling up my car when I'm not looking

)

Still strange that the light won't stay on. Maybe the ABS sensor is on its way out, but it still would not explain the constant lack of speedometer activity and the temporary ABS light illumination. The speed determination and the ABS information are derived from the same 'packed' of information from the sensor right? As in, only 12v down to the sensor and alternating voltages going back to the car brains.

Mike Noc · 21st December 2023, 08:03

Strange that the system is working with the ABS light illuminated. Might be worth checking and cleaning the ABS plug connections, if only to rule them out.

Geoff130 · 21st December 2023, 09:03

There's also the possibility the IPK is faulty too, I forget how to select it using the trip mileage button but there is a test that will check all the gauges and lights in the IPK.

Savestones · 10th January 2024, 17:37

Quote:

Originally Posted by Geoff130

There's also the possibility the IPK is faulty too, I forget how to select it using the trip mileage button but there is a test that will check all the gauges and lights in the IPK.

Glad to report that the IPK is still fully functional, and also the sensors are clean. I now resorted to changing out the bearings, and while there I'm also replacing the front right ABS sensor.

Still not a clue why the ABS light does not stay illuminated, but I guess some things will forever remain a mystery

DMGRS · 11th January 2024, 10:30

That's very odd - it should of course keep the light on if there's a fault with the sensor readings.
My experience with these cars is that they're overly-sensitive to issues like this, not the other way around!

If you need sensors or bearings, we have a huge selection in our Shop - and we ship world-wide too.

Savestones · 22nd February 2024, 11:16

So a quick update on this issue.

Finally got around to changing the front wheel bearings. This eliminated the shaking in the pedal and sterring wheel I experienced when braking, but I have yet to get any sign of life from the speedometer.

Checked the gauge cluster with the build in test function, and all seemed to be working just fine. ABS light will stay illuminated when fully unplugging the front right ABS sensor, so the light also works. Scanned for codes using TOAF which threw up an ABS error for the front right sensor.

Up next is changing the ABS sensor, which will just be soldered to the cable in the engine bay (I don't want to risk any potential poor connections due to the broken plastic connectors). Will be back once that is all done to report on the issue. Praying it's not an electrical issue further under the dash or something like that.

20th December 2023, 07:13	#1
Savestones Regular poster MG ZT-T Join Date: Dec 2021 Location: Arnhem, Netherlands Posts: 62 Thanks: 10 Thanked 6 Times in 6 Posts	Speedo not working, but no ABS light! In this sea of ABS issues I have an interesting fault on my car. The speedo will not work reliably, sometimes coming back to life for a bit only to fall back to 0 km/h again after the first (smooth or sharp) bump in the road or hard braking action. Now it's mostly stuck at 0 km/h. The right front wheel bearing has play, so the symptoms are not completely unexpected. However, the funny thing is is that the ABS light does not stay on. So far, in ~200 kms it has popped on 3 times for less than 2 seconds each time. Also, braking seems normal enough. I'm confident that swapping out the wheel bearing will resolve the issue I'm experiencing, but could anyone shed some light on the combination of faulty speedo without an ABS light? As far as I understand my ABS light should be on, and I'd love to understand the ABS system on these cars a bit better

20th December 2023, 08:56	#3
planenut Regional Secretary Rover 1.8T Tourer Join Date: May 2007 Location: Heathrow Posts: 6,955 Thanks: 1,551 Thanked 2,036 Times in 1,264 Posts	As I understood, a faulty o/s/f abs sensor could affect the signals to the speedo and the fuel gauge. Good luck with it, but fear not, someone with more knowledge and more advice will be along soon. Have a read through this thread. https://www.the75andztclub.co.uk/for...d.php?t=326201 Last edited by planenut; 20th December 2023 at 09:02..

11th January 2024, 10:30	#9
DMGRS Discount MG Rover Spares Rover 75 CDTi, 2x MG ZS180 Join Date: Jun 2011 Location: Hythe, Southampton Posts: 11,320 Thanks: 456 Thanked 3,377 Times in 2,027 Posts	That's very odd - it should of course keep the light on if there's a fault with the sensor readings. My experience with these cars is that they're overly-sensitive to issues like this, not the other way around! If you need sensors or bearings, we have a huge selection in our Shop - and we ship world-wide too. __________________ Your trusted MG Rover specialist! Tel: 02380 001133 / Email: [email protected] We now have a 'chat' function on our site for even quicker replies. Give it a try! Remember - discount code FORUM5 for 5% off

22nd February 2024, 11:16	#10
Savestones Regular poster MG ZT-T Join Date: Dec 2021 Location: Arnhem, Netherlands Posts: 62 Thanks: 10 Thanked 6 Times in 6 Posts	Quick update So a quick update on this issue. Finally got around to changing the front wheel bearings. This eliminated the shaking in the pedal and sterring wheel I experienced when braking, but I have yet to get any sign of life from the speedometer. Checked the gauge cluster with the build in test function, and all seemed to be working just fine. ABS light will stay illuminated when fully unplugging the front right ABS sensor, so the light also works. Scanned for codes using TOAF which threw up an ABS error for the front right sensor. Up next is changing the ABS sensor, which will just be soldered to the cable in the engine bay (I don't want to risk any potential poor connections due to the broken plastic connectors). Will be back once that is all done to report on the issue. Praying it's not an electrical issue further under the dash or something like that.

20th December 2023, 08:25	#2
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,550 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Unplug one of the ABS sensors and turn key to position II - does the ABS light stay on? If not Mr Previous Owner may have bodged it due to another problem - not unknown for it to be wired into another LED on the IPK display.

21st December 2023, 08:03	#6
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,550 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Strange that the system is working with the ABS light illuminated. Might be worth checking and cleaning the ABS plug connections, if only to rule them out.

21st December 2023, 09:03	#7
Geoff130 Loves to post MG ZT 190, Rover 75 CDTi, Honda VFR 750, Honda CB550F Join Date: Aug 2010 Location: Derby Posts: 393 Thanks: 75 Thanked 36 Times in 28 Posts	There's also the possibility the IPK is faulty too, I forget how to select it using the trip mileage button but there is a test that will check all the gauges and lights in the IPK.