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Anti Lock ECU replacement

MrScruffs
Posts: 14
Joined: Thu Jan 31, 2019 2:18 pm
Location: West Sussex

Anti Lock ECU replacement

Postby MrScruffs » Fri Feb 15, 2019 1:36 pm

Hello Everyone,

I've been lurking on the board for a week or so, soaking up the expert advice and opinions of long-time XJ40 owners, and awaiting the sunshine to take some photos of my (new to me) 1989. Daimler 4.0 in lovely Dorchester Grey.

However, the photos will have to wait for the weekend when I tackle the ABS problem that is keeping it off the road. The Anti Lock dashboard light is permanently on from the first turn of the key. I picked it up last weekend as a running project with a recently expired MOT. Aside from the light being on she runs and drives great, with good general braking, no pulling in either direction, and a 'normal' feeling pedal.

Reading through the many topics here, and elsewhere, it would seem that the primary areas to investigate first are sensors, Anti Lock ECU, and an Over Voltage Relay? Although I think that my car as an October 1989 Daimler is actually a 90MY and has no Over Voltage relay? I certainly can't find one in the boot near the fuel filler!

My question is about the Anti Lock ECU. I decided that it was cheap enough to buy a known good replacement from the web during the week and fit it over the weekend before moving on to messier jobs. If I replace the ECU, should the light go out immediately or will I have to take her out for a spin to clear the warning?

Thanks in advance!
--
1989 Daimler 4.0 in Dorchester Grey
1995 Land Rover Defender 90 in many colours

katar83
Posts: 2714
Joined: Tue Aug 23, 2011 11:17 am
Location: Cambridge

Re: Anti Lock ECU replacement

Postby katar83 » Fri Feb 15, 2019 1:57 pm

My 94 ABS ECU was proper knackered, solder joints clearly cracked inside. I suspect earlier ECUs might have the same fault but resoldering it fixed is straight away. You will need to take the car for a drive to clear ABS codes.
1997, 4.0 LWB X300 - Unlucky car but still a daily driver.
1988, 3.6S XJS - Never ending restoration project.
1994, 3.2S X300 - Accident damaged, October 2015. Gone!
1994, 3.2S XJ40 - Long gone.

MrScruffs
Posts: 14
Joined: Thu Jan 31, 2019 2:18 pm
Location: West Sussex

Re: Anti Lock ECU replacement

Postby MrScruffs » Fri Feb 15, 2019 2:57 pm

Hi, thanks for the reply! Luckily I have a short private road right next to my house so I guess I'll be driving up and down that a bit to see if it works! :)
--
1989 Daimler 4.0 in Dorchester Grey
1995 Land Rover Defender 90 in many colours

naki_k
Super Moderator
Posts: 28512
Joined: Sun Feb 21, 2010 9:25 pm
Location: Kirton, nr Boston, Lincolnshire

Re: Anti Lock ECU replacement

Postby naki_k » Fri Feb 15, 2019 11:06 pm

katar83 wrote:My 94 ABS ECU was proper knackered, solder joints clearly cracked inside. I suspect earlier ECUs might have the same fault but resoldering it fixed is straight away. You will need to take the car for a drive to clear ABS codes.


Agree yes. That’s certainly the first thing to try. Free fix, just your time.
88 3.6 XJ6 PDH/CEM
90 Range Rover Vogue SE 3.9 V8 LPG
91 4.0 XJ6 Manual
92 4.0 XJR Manual
92 4.0 XJR
93 3.2s - 4.0 Manual conv
93 4.0 Sovereign
93 6.0 XJ81 DD6 x2
93 6.0 XJ81 XJ12
94 4.0 XJR
94 4.0 Daimler
96 4.0 X306 XJR
96 4.0 X300 D6
97 4.0 X300 Sport Manual
2000 LR Discovery ES TD5 A
Breaking 40/ 300

naki_k
Super Moderator
Posts: 28512
Joined: Sun Feb 21, 2010 9:25 pm
Location: Kirton, nr Boston, Lincolnshire

Re: Anti Lock ECU replacement

Postby naki_k » Fri Feb 15, 2019 11:13 pm

The OV relay is for 3.6/2.9 models only.
Bit by bit they changed 90% of the parts on these cars between and early and late models.
88 3.6 XJ6 PDH/CEM
90 Range Rover Vogue SE 3.9 V8 LPG
91 4.0 XJ6 Manual
92 4.0 XJR Manual
92 4.0 XJR
93 3.2s - 4.0 Manual conv
93 4.0 Sovereign
93 6.0 XJ81 DD6 x2
93 6.0 XJ81 XJ12
94 4.0 XJR
94 4.0 Daimler
96 4.0 X306 XJR
96 4.0 X300 D6
97 4.0 X300 Sport Manual
2000 LR Discovery ES TD5 A
Breaking 40/ 300

MrScruffs
Posts: 14
Joined: Thu Jan 31, 2019 2:18 pm
Location: West Sussex

Re: Anti Lock ECU replacement

Postby MrScruffs » Fri Feb 15, 2019 11:40 pm

naki_k wrote:The OV relay is for 3.6/2.9 models only.
Bit by bit they changed 90% of the parts on these cars between and early and late models.


Thank you for the clarification. I’m very slowly learning where she sits in the history of the model. There are lots of little jobs to do, but I believe that if I can get the abs issue sorted then I’ll be able to get an MOT and then spend a happy spring tinkering away...

...I suppose these are likely to be words that come back to bite me in 6 months!
--
1989 Daimler 4.0 in Dorchester Grey
1995 Land Rover Defender 90 in many colours

MrScruffs
Posts: 14
Joined: Thu Jan 31, 2019 2:18 pm
Location: West Sussex

Re: Anti Lock ECU replacement

Postby MrScruffs » Sat Feb 16, 2019 8:55 am

Well... it’s not the Anti Lock ECU... :(
--
1989 Daimler 4.0 in Dorchester Grey
1995 Land Rover Defender 90 in many colours

katar83
Posts: 2714
Joined: Tue Aug 23, 2011 11:17 am
Location: Cambridge

Re: Anti Lock ECU replacement

Postby katar83 » Sat Feb 16, 2019 10:06 am

Time to check each sensor now, have you got a multimeter and know how to use it? :ugeek:
1997, 4.0 LWB X300 - Unlucky car but still a daily driver.
1988, 3.6S XJS - Never ending restoration project.
1994, 3.2S X300 - Accident damaged, October 2015. Gone!
1994, 3.2S XJ40 - Long gone.

MrScruffs
Posts: 14
Joined: Thu Jan 31, 2019 2:18 pm
Location: West Sussex

Re: Anti Lock ECU replacement

Postby MrScruffs » Sat Feb 16, 2019 3:53 pm

I do not have a multimeter right now, but I did just do the blink test.

I got codes 21 & 32

21: defective valve/cable harness/power transistor in ECU.

Check indicated solenoid valve / terminals for short or interruptions

Indicated Solenoid: Main Valve

32: Sensor front right.
--
1989 Daimler 4.0 in Dorchester Grey
1995 Land Rover Defender 90 in many colours

naki_k
Super Moderator
Posts: 28512
Joined: Sun Feb 21, 2010 9:25 pm
Location: Kirton, nr Boston, Lincolnshire

Re: Anti Lock ECU replacement

Postby naki_k » Sat Feb 16, 2019 7:36 pm

MrScruffs wrote:I do not have a multimeter right now,.


That’s your first issue to address then. That’s one of the most essential tools you will need to run and maintain a car like this.
You can get a basic unit for under £10.
I keep about 6 of these dotted around the place, so there’s always one to hand! They are that important!
88 3.6 XJ6 PDH/CEM
90 Range Rover Vogue SE 3.9 V8 LPG
91 4.0 XJ6 Manual
92 4.0 XJR Manual
92 4.0 XJR
93 3.2s - 4.0 Manual conv
93 4.0 Sovereign
93 6.0 XJ81 DD6 x2
93 6.0 XJ81 XJ12
94 4.0 XJR
94 4.0 Daimler
96 4.0 X306 XJR
96 4.0 X300 D6
97 4.0 X300 Sport Manual
2000 LR Discovery ES TD5 A
Breaking 40/ 300