MG TF LE 500 ABS Issue

Hi all,
Looking for some thoughts from the hive mind, so I’ve an MG TF LE500 and the ABS light never comes on, even during start up, I’ve tested the ABS system and it doesn’t work. I’ve pulling out the instrument cluster to see if anyone’s physically disabled the ABS LED but it looks ok.
The 15A fuse in the main fuse box under the steering column and the 60A in the engine bay both test ok. I can’t find a wiring diagram for the ABS Pump module ‘pin outs’ but I’m getting +12v on some of the brown wires and my earths are good and Pscan won’t communicate with the ABS module.
Before I buy another ABS module, a couple of questions,
1. does anyone actually know if the LE 500 ABS pump module is the same as the TF, because I’ve found out that the ABS Reluctor rings are unique to the LE 500?
2. Does anyone, have any other ideas as to why my ABS light isn’t on, if I unplug the ABS pump module connector the light still doesn’t come on?
Thanks in advance
Mark

As you can see from being overwhelmed with replies very few on here own or know anything about these models (including me) all I know is there are apparently no wiring diagrams or manuals for them. All I can suggest is try to find the part no on the Abs module to see if it's the same as the TF in which case you can use info available for that. Once you have the part no you can google it and hopefully it's fitted to other cars which may help with info/purchase.

Re pscan have you tried contacting them to see if pscan does/should support it? you could also try posing this question on the dedicated pscan forum on here.

Lastly have you posted on any other forums like MG Rover.org, MGF regiser and T-Bar somebody must know something, sorry I can't be more help.

Hi santapod,

I have a Service Procedure Manual for Chinese TF issued by NAC MG UK dated 09/2008 and very few things were changed from the MG Rover one.

If you have no light, no Pscan connection, it sounds like power supply issue or earth (or someone cut a wire for MOT)

The power supply to the ABS Module shows the F21 15amp fuse you mention, plus three links under bonnet. Link 2 @ 60 amps, Link 4 @ 40 amps, and Link 6 @ 60 amps.

Earth from the ABS Module is from Earth Point K108 which is on RH Front Wing to the rear of headlight.

Warning lamp on instrument cluster should be pin 7 coming from pin 21 on ABS Module

Cheers Mark

Hi,
Thanks for you help and advice Mark, I'll be taking another look at the weekend, as I do want to re-commission the ABS before an 'eagle eye'd' MOT tester spots the missing light. Yes I'm beginning to think someone has cut a wire somewhere for the MOT.
Looks like the LE500's run the same ABS module at the TF's (SRB 101570) but maybe it runs different software to account for the change in the number of teeth on the Reluctor rings, (TF 43, LE 42)

Re, the warning lamp, I'll test for continuity between P7 and P21, would you happen know what condition it expects to receive from the ABS Module, if there's an ABS fault , +12v, or earth, or maybe something in between . E.G could it be that when the ABS module detects a fault, it puts +12v on Pin 21 of the module to light the warning lamp, or maybe I'm over simplifying the circuit?

Thanks again for your help
Mark

If Pscan is not seeing the ABS module, that indicates the ABS module is not powering up.

Disconnect the ABS module connector and check power to the two BROWN & PINK wires on Pins 17 and 18. Then with Ignition On check power to GREEN & PINK wire on Pin 15. If OK then check continuity of two BLACK wire on Pins 16 and 19 to a good Earth. This will show you if Power and Earth are good to module. If that is OK it would tend to indicate a dead Module as Pscan should pick it up if it is powered up but has a sensor fault or such.

To check the ABS warning light , drop the fuse box cover in passenger footwell and get to the 20 row connector (two rows of ten) at the top of fuse tray. This goes to the instrument cluster. The BLUE & RED wire on pin 7 goes from ABS Module to ABS Warning Light. Do a continuity test back to ABS Module plug. If OK reconnect ABS Module plug and check voltage on this pin. Not sure if it is volt on or volt off system but you should see on / off pulse when ignition turned on if it is going through start up sequence, even if just to check the bulb I assume.

So if you have Power and Earth to ABS Module, and a test pulse going to ABS Warning Light I would assume broken bulb of wire cut in instrument cluster/connection. But if Pscan is working it should find that.

Good Luck

Thanks again for your help Mark,
Will run some more tests over the weekend.
I've also managed to get hold of a 'known good' ABS module to help with testing.

Cheers
Mark

Well done to both Marks for this info , top lads !

A classic example of why the T-bar community is so important, it was also illustrated with the bell crank query running in parallel with this.
Without this community there would be significantly fewer of our cars on the roads, ever niggle outside the owners capacity would require professional services & at what cost.
We are also doubly blessed with Pscan & Technozen. Without these two guys we would be heartedly shafted.
I am not familiar with fora for other cars, can they be as good as this (rhetorical question)?
M

Hi Mark
So I have a faulty ABS Module. I tested with the replacement plugged in and the ‘new’ module communicates with Pscan. 😊 but the ABS light still doesn’t work.
I’ve also tested the BLUE \ RED wire from the ABS module plug through to the ’20 row’ connector above the fuse box and the wire is good.
Incidentally, the faulty ABS module sends a perm +12v out on the BLUE \ RED and the good unit sends +12v for 3 seconds, so that all looks good.

One last question, is it still a BLUE \ RED wire from the other side of the ’20 row’ connector up to one of the two instrument cluster plugs, as I’d like to test this last link next weekend before I look to get the cluster checked out and repaired?

Thanks gents
Mark

Hi Mark,

Yes same colour wire to instrument cluster, just a bit thinner. ( 0.75 down to 0.5mm)

Timings of ABS light pulse sounds about right, just checked my start up sequence and ABS light came on for 3 seconds before going out when ignition turned on.

I'm sorry , but it sounds like a previous owner knew about faulty ABS module , had a permenant ABS light, and dealt with the light not the problem. Hope no damage. Good News is that binnacle is only a 5-10 min job to remove. No need to remove steering wheel/air bag. Easy to take apart. Got the t-shirt... LOL.

Good luck , Mark

.

Hi,

Had a similar problem on my TF 160 when I bought it 8 years ago. garage I bought from swore blind that it was ok, but I road tested it and anchored up so the wheels locked with their mechanic in the car with me....he had now idea.
I eventually found the problem myself, a black earth wire was broken off the common earth stud in the engine bay next to the air filter on the inside wing. I refitted the wire and the ABS was ok after.

Not saying its the same with your car, but worth checking.

Sundance

]Hi All, Just to provide a brief update. I finally managed to fit a new instrument cluster to my LE500 and ‘hey presto’, my ABS light now ‘lights up’, and so it was a fault with the ABS LED on my old cluster. There’s also an additional engine management warning light at the top of the dash that wasn’t working on my old unit, so it does look like the LED’s are prone to failure. Photo attached for reference and now the fun beings. Do I have the old unit repaired, or try and get the millage ‘corrected’
Thanks for all the comments and assistance.
Regards
Mark