No Start Fixed Now abs fault

Ok I have the no start fixed thanks to this forum, But now I have the 3 amigo,s alight, I cant get any communication with the abs using the usual scanner , so going through the OB2 section on my Verus, Engine management . I get code P0501 Vehicle speed sensor "A" Range performance. I have spent a long time searching on the web, But so many different suggestions. If this is a speed sensor, Not wheel sensor, Where is it located.


Paul

Reluctant Ring is what the ABS Sensor picks up the speed. Depending on the age this could worn or dirty enough to cause problem. Try cleaning the ring first and check the ABS Sensor for any wire fraying.

There's no separate speed sensor on the FL1. The vehicle speed is taken from the ABS ECU, using the wheel sensors.
3 Amegos is most likely to be the brake light switch

I think the P0501 may be a red herring - that's coming from the engine ECU and not the ABS ECU. However the 2 talk to each other to determine vehicle speed which is what that error relates to. Is the speedo working OK?

What Nodge says is true, replacing the brake switch often cures 3 Amigos but you should really do what you were trying to do first and read the diag codes from the ABS ECU. If P0501 is to be believed then I can't see it being the brake switch, it will be something else like 1 of the sensors - however, you'll need to get the codes read to find out which wheel to look at. If P0501 is a red herring then brake switch is likely, but maybe sensor/reluctor/wiring, maybe the ABS pump/modulator (that's what its been the 2 times I've had the Amigos).

When I've had the Amigos, I pop down my local indie Land Rover place, cover his palm with coins and he reads the codes.

I have ohs tested the wheel sensors, I will put a scope on them today to see if I am getting a good signal, I did put the meter on ac volts and spin the wheel and the voltage did rise, So I thought the semnsors where fine. How can I test the brake switch, And also why do I have no comunication with the abs, I can get in to the ecu?.

That should have been OHMS tested the sensors , sorrry

Not sure on later models, but most/all engine ECUs use a different comms protocol to the ABS ECU. ODBII is only a engine management protocol for emmisions regulatory reasons - it does not cover the ABS. I don't think the cheap ODB dongles even try and connect to the ABS ECU. The generic hand held units that 'support' ABS will only support the ABS protocols of cars they are designed for - whether they support the protocols used by the Wabco, Teves Mk20 or Teves Mk25 ABS ECUs used in Freelander should be specifically checked. Remember they are "old" systems that predate even regulatory ODB diagnostics on the engines.

It is this minefield of protocols, together with LRs desire not to publish any info on it, that enable companies to sell LR specific diag tools with stupidly high prices.

It's quite common to get random codes stored in the ECU memory.

When I first got my current TD4 SE auto I read all codes logged, as I always do. Mine came up with a speed sensor error on the EDC. The TCM showed multiple faults too. The ABS ECU showed a low voltage code as did the airbag ECU.
All my ECUs worked correctly without showing any warning lights.

This is why I suggested the brake light switch. Your speed sensor fault is most likely a Red Herring, as GG has pointed out.

Verus? Scope? Your diagnostic kit is probably worth more than your Freelander

If you scope each sensor at its connector you should get a clean AC signal that increases in frequency and amplitude with speed. This will test the sensor and reluctor for damage or dirt. Often, The sensors get clogged with magnetic debris.

I've not tested a brake light switch, but as I recall it consists of two switches, one normally open and one normally closed. It's easier just to replace it with an upgraded version, though.

If you eliminate all the electrical gremlins, sometimes you have to clear the codes and/or drive above a certain speed for a small distance for the ABS unit to reset the lights.

Today I have tested fuses F2 F7 F35 F11 F8 all live with the ignition on nothing with the ignition off, I think F11 and F8 should be live at all times, also I forgot to mention the Speedo does not work.



I am going to try to scope the wheel sensors tomorrow, I will try to do them from the abs plug, and the if there is a wiring problem it will show up.


As for the Verus, yes expensive, But it still has not fount this problem, Probably me more than the Verus... It will not communicate with the abs on this car.


Thanks for al the input. Your help is worth more than the verus.

Not sure what splice joint 44 is, but you might be on the wrong track there.

Speedo not working is consistent with your error code.

how can iI insert the wiring diagram? F11 is a direct live feed to the abs unit

... and some bedtime reading for you:

As the speedo is not working P0501 is not a red herring.

I'm not sure what gives the speedo its signal? Is it the CCU which is why the ABS ECU feeds it with the vehicle speed?

I'm not so sure that the problem is "a wheel sensor" - or its reluctor or wiring. Maybe I'm wrong, but I don't think I've heard of an ABS sensor taking out the speedo before.

The ABS ECU invokes TC if it detects a wheel is turning faster than the vehicle speed. Therefore the vehicle speed is not calculated on 4 sensors which would be dropped if only 1 fails. I would imagine that vehicle speed is calculated on the closest matching 2 or 3 sensors. Maybe with a fail-safe that it cant change too quickly.

I've therefore got a strong suspicion that your problems can not be identified by checking each wheel sensor - even at the ABS ECU. Maybe a mouse has taken out the loom somewhere, breaking multiple wires.

This might even be a dead ABS ECU.

Still think you need the codes read.

Actually the CCU would use vehicle speed to disable functions - such as opening the back door I suppose.

Yes I understand I need to get the codes read, But if I have no comunication with the abs, how am I going to do it

I am assuming the abs control module is all part of the abs unit, if this is the case can I just get a second hand one and change it to see if this is the problem, or are they coded?.

I would take it to a Stealers/Indie to have the codes read - presumably if they can't read the codes then the ABS ECU is stuffed - and they won't charge you as the codes couldn't be read.

If they can read the codes, then you've identified where to look.

I don't think the ABS ECUs are coded - certainly the Wabco units are not and I think the Teves units aren't either. There have been reports that supposedly Freelander specific diag tools (think it was the i930) could not communicate with a Teves Mk20 - but the Teves Mk25 used in your 2003 car should be OK with a Freelander specific device.

The Wabco ECUs are under the drivers seat, but looking on the web the Teves unit looks integrated to the modulator/pump unit. However, if you need one, they don't look expensive on eBay to buy the combined unit. Hopefully you can swap just the ECU bits over as then you don't have all the trouble of brake fluid everywhere and bleeding the system. Might be worth seeing what Rave has to say.

As GG said. The new information of the speedo not working changes things massively. Either the ABS ECU has failed in some way. Or the power feed to it has somehow been disrupted. Definitely worth getting the codes read.
If there's no power at the ABS ECU then the codes most likely can't be read.

Nodge68 said:

As GG said. The new information of the speedo not working changes things massively. Either the ABS ECU has failed in some way. Or the power feed to it has somehow been disrupted. Definitely worth getting the codes read.
If there's no power at the ABS ECU then the codes most likely can't be read.

Click to expand...

Do the Teves ECUs control the Amigos on the dash directly? I know on my Wabco there are 4 wires coming from the ABS ECU that drive/power the lights directly. If the ECU had no power, the lights would not light.

I know the later dashes are more 'networked' - is it that the ABS ECU tells some other ECU which lights to power? If so, if that ECU gets no message from the ABS ECU maybe it lights them for that reason - and maybe its that ECU which needs the codes read to see if there's a message saying that there's no communication from the ABS.