940 ABS light

Volvanman · Sep 30th, 2014, 10:09

Hello all,

I have a 98 940 LPT. The ABS warning light has remained on for the past few months (ABS still functions correctly), and with MOT looming in November it is time to try to get to the bottom of the problem.

I have researched on here, and have made my own LED code reader. I have the list of codes for ABS faults, and predictably and annoyingly it is giving me the code 1-1-1, indicating no fault recorded.

My tester is configured as follows:

LED +ve terminal to pin 16.
LED -ve terminal to pin 3, with an additional terminal linked to the LED -ve applied to pin 5 for approx. 2 seconds... This generates the 1-1-1 code.

So now I have hit a wall. Can anybody offer any further advice? Obviously a fault must exist for the light to on in the first place, so why is there no fault recorded?

Many thanks in advance,

Regards,

Jerry

Alasdair1 · Sep 30th, 2014, 11:31

Mine did the same. I didn't have a reader at the time and eventually I disconnected the battery overnight (make sure you have the radio code) and on reconnecting it the light went off. I put it down to a blip in the system. It could also be a sensor about to fail or perhaps dirt in the toothed wheel.

Alasdair

Forrest · Sep 30th, 2014, 21:38

I did once have an ABS ecu go faulty. It's the metal box with a red (for your model year) Bosch label on it behind the driver's kick panel. If the fault persists it might be worth swapping this for a known good one. They are generally very reliable which means second hand ones are usually OK.

It may also be worth checking battery and alternator voltage and that the various under-bonnet earth connections are OK. Electrical issues can lead to spurious warning lights too.

CTCNetwork · Sep 30th, 2014, 23:32

Hi,

Is the speedo working correctly?

Des. . .

Volvanman · Oct 2nd, 2014, 07:56

Thanks for advice so far, it is a very frustrating problem.

I have a spare vehicle that I use for spares, so I will try the ABS ECU from that & see if it clears.

Other than that, no improvements so far.

Des, the speedo works fine & always has done, but an interesting question - is the speedo function somehow related?

Anymore suggestions will be gratefully accepted,

Regards,

Jerry

Alasdair1 · Oct 2nd, 2014, 09:57

It may sound like a daft question but what position is the igntition key in when your reading the codes. I think it should be in II. Apologies if I'm stating the obvious. As for the speedo I think it takes a pulse from the ABS sensor in the rear diff. I once as a last resort in one of my old Volvos which had an ABS fault rewired the ABS light to the oil pressure light. Came on with ignition and off once started.

Hope you get it sorted
Alasdair

CTCNetwork · Oct 2nd, 2014, 10:10

Hi,

Yes. The ABS ECU takes a reading from a shared sensor in the diff. The sensor can fail or be faulty so then the speedo will behave erratically or not at all.
Having said that, the speedo can work just fine but the sensor still be faulty!

As Alasdair says you should check the continuity of the cable from the rear sensor. But you do really need to get you codes read to properly identify the area where the fault lies. It may be worth while going to a good Volvo Indie and asking nicely to see if they could read your codes properly.

Des. . .

peterl · Mar 8th, 2016, 17:28

Jerry Did you ever sort the problem out OK only my 940 2.3lpt has the ABS warning light playing up intermittently Sometime it goes off once the engine starts and other times it stays on.
Cheers
Peter

Volvanman · Mar 8th, 2016, 20:07

Hello Peter,

I replaced both front sensors which stopped the warning light illuminating for quite a while. I've not re-read this thread, so I might be wrong, but as I recall the warning light was on permanently. Replacing the sensors cured that, but recently the warning light started illuminating intermittently. It would just come on randomly during a journey & stay on, but be off again when you restarted the car later. I know that it is not the right way to deal with it, but I'm afraid I got rather bored with looking at it & have now removed the bulb...

Sorry not to be of much help, but now the thread has been bumped up, perhaps someone else will be better able to help...

rogerthechorister · Mar 8th, 2016, 20:54

The ABS warning light comes on if the codes from any of the three sensors are missing - or interrupted enough. This can often be the wire from the diff - but then the speedo plays up too. If the front sensors or the wires to them are iffy you should get a code from the blink reader, but you can also measure the resistances using an avometer or whatever they are called these days.

If your codes and resistances are OK the most likely fault is sh1t in the tone rings, so dismantle both front wheel assemblies to get at the tone rings without mullering everything else and jetwash the wossname out of them.

The senders cost the urf so replacing them on spec is DEFINITELY the last resort.

Sep 30th, 2014, 10:09	#1
Volvanman Slewmeister... Last Online: May 15th, 2019 15:30 Join Date: Dec 2013 Location: Market Rasen	940 ABS light Hello all, I have a 98 940 LPT. The ABS warning light has remained on for the past few months (ABS still functions correctly), and with MOT looming in November it is time to try to get to the bottom of the problem. I have researched on here, and have made my own LED code reader. I have the list of codes for ABS faults, and predictably and annoyingly it is giving me the code 1-1-1, indicating no fault recorded. My tester is configured as follows: LED +ve terminal to pin 16. LED -ve terminal to pin 3, with an additional terminal linked to the LED -ve applied to pin 5 for approx. 2 seconds... This generates the 1-1-1 code. So now I have hit a wall. Can anybody offer any further advice? Obviously a fault must exist for the light to on in the first place, so why is there no fault recorded? Many thanks in advance, Regards, Jerry

Sep 30th, 2014, 23:32	#4
CTCNetwork Forum Support Team Join Date: Dec 2004 Location: Liège, Belgium View Photos By: CTCNetwork	Hi, Is the speedo working correctly? Des. . . __________________ Density:- Not just a measurement ~ It's a whole way of Life.! ! ! I drive a Volvo, Please Don't Get In My Way! OldVolvos4Ever He shows up. People die. He vanishes. People should not be afraid of their governments. "He'll deliver more justice in a weekend than 10 years of your Governments should be afraid of their people... "V" courts & tribunals. Just stay out of his way." "I plan to."

Oct 2nd, 2014, 10:10	#7
CTCNetwork Forum Support Team Join Date: Dec 2004 Location: Liège, Belgium View Photos By: CTCNetwork	Hi, Yes. The ABS ECU takes a reading from a shared sensor in the diff. The sensor can fail or be faulty so then the speedo will behave erratically or not at all. Having said that, the speedo can work just fine but the sensor still be faulty! As Alasdair says you should check the continuity of the cable from the rear sensor. But you do really need to get you codes read to properly identify the area where the fault lies. It may be worth while going to a good Volvo Indie and asking nicely to see if they could read your codes properly. Des. . . __________________ Density:- Not just a measurement ~ It's a whole way of Life.! ! ! I drive a Volvo, Please Don't Get In My Way! OldVolvos4Ever He shows up. People die. He vanishes. People should not be afraid of their governments. "He'll deliver more justice in a weekend than 10 years of your Governments should be afraid of their people... "V" courts & tribunals. Just stay out of his way." "I plan to."

Mar 8th, 2016, 17:28	#8
peterl VOC Member Last Online: Mar 13th, 2016 17:33 Join Date: Jan 2011 Location: Barrow upon Humber	Jerry Did you ever sort the problem out OK only my 940 2.3lpt has the ABS warning light playing up intermittently Sometime it goes off once the engine starts and other times it stays on. Cheers Peter __________________ Current 940 2.3 Auto

Mar 8th, 2016, 20:07	#9
Volvanman Slewmeister... Last Online: May 15th, 2019 15:30 Join Date: Dec 2013 Location: Market Rasen	Hello Peter, I replaced both front sensors which stopped the warning light illuminating for quite a while. I've not re-read this thread, so I might be wrong, but as I recall the warning light was on permanently. Replacing the sensors cured that, but recently the warning light started illuminating intermittently. It would just come on randomly during a journey & stay on, but be off again when you restarted the car later. I know that it is not the right way to deal with it, but I'm afraid I got rather bored with looking at it & have now removed the bulb... Sorry not to be of much help, but now the thread has been bumped up, perhaps someone else will be better able to help... __________________ Regards - Jerry 97 940 HPT, 25mm H&R spacers, Tethys alloys - 225/45 rear & 215/45 front, slotted discs all round & EBC Yellowstuff pads, MBC @ 14psi, 19t, blue injectors, 3" turbo back single silencer system... 96 960 3.0 Auto

Sep 30th, 2014, 11:31	#2
Alasdair1 Master Member Last Online: Jul 19th, 2017 12:38 Join Date: Aug 2010 Location: Inverness	Mine did the same. I didn't have a reader at the time and eventually I disconnected the battery overnight (make sure you have the radio code) and on reconnecting it the light went off. I put it down to a blip in the system. It could also be a sensor about to fail or perhaps dirt in the toothed wheel. Alasdair

Sep 30th, 2014, 21:38	#3
Forrest VOC Member Last Online: Today 01:54 Join Date: Feb 2008 Location: Gloucester	I did once have an ABS ecu go faulty. It's the metal box with a red (for your model year) Bosch label on it behind the driver's kick panel. If the fault persists it might be worth swapping this for a known good one. They are generally very reliable which means second hand ones are usually OK. It may also be worth checking battery and alternator voltage and that the various under-bonnet earth connections are OK. Electrical issues can lead to spurious warning lights too.

Oct 2nd, 2014, 07:56	#5
Volvanman Slewmeister... Last Online: May 15th, 2019 15:30 Join Date: Dec 2013 Location: Market Rasen	Thanks for advice so far, it is a very frustrating problem. I have a spare vehicle that I use for spares, so I will try the ABS ECU from that & see if it clears. Other than that, no improvements so far. Des, the speedo works fine & always has done, but an interesting question - is the speedo function somehow related? Anymore suggestions will be gratefully accepted, Regards, Jerry

Oct 2nd, 2014, 09:57	#6
Alasdair1 Master Member Last Online: Jul 19th, 2017 12:38 Join Date: Aug 2010 Location: Inverness	It may sound like a daft question but what position is the igntition key in when your reading the codes. I think it should be in II. Apologies if I'm stating the obvious. As for the speedo I think it takes a pulse from the ABS sensor in the rear diff. I once as a last resort in one of my old Volvos which had an ABS fault rewired the ABS light to the oil pressure light. Came on with ignition and off once started. Hope you get it sorted Alasdair

Mar 8th, 2016, 20:54	#10
rogerthechorister Rogerthechorister Last Online: Dec 16th, 2023 02:15 Join Date: May 2006 Location: Rochester	Usually... The ABS warning light comes on if the codes from any of the three sensors are missing - or interrupted enough. This can often be the wire from the diff - but then the speedo plays up too. If the front sensors or the wires to them are iffy you should get a code from the blink reader, but you can also measure the resistances using an avometer or whatever they are called these days. If your codes and resistances are OK the most likely fault is sh1t in the tone rings, so dismantle both front wheel assemblies to get at the tone rings without mullering everything else and jetwash the wossname out of them. The senders cost the urf so replacing them on spec is DEFINITELY the last resort. __________________ B234F estate, H reg 100k miles. RIP melted B280E. 760T estate, F reg 133k miles. 940 Sport M90 estate, N reg 170k miles. 940 Sport M90 estate, N reg 100k miles, ex Lovejoy. 960 Estate, N reg, 56k miles, blown up and sold.

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