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ABS light (intermittent)

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Hello everyone. Im sure this is a common fault and im not asking how to fix it, I just want some advice on how to diagnose it. 

I have used the car's own self diagnostic system and found that there are no DTC codes stored. I would like to know which of the four wheels has the fault so I can direct my attention in the correct place and save myself a lot of time and effort.

 I dont have the kind of money to start buying Delphi diagnostic equipment and I dont want to waste money on something that returns the same result as the self diagnostic system i.e. "DTC none". Does anyone know of anything on the market that will pin point where my ABS fault lies via the diagnostic port? My vehicle is a Ford Focus 1.6 2002.

Many thanks.

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The so called ‘self test’ is a complete waste of time.

you'd probably be best to look at getting a lead from eBay and downloading Forscan, so this setup will cost you say, £20.

Then you can atleast see what is coming up and start to diagnose from that information. 

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Being the owner of obd code reader from tunnelrat electronics (their advertised price includes uk postage) and free forscan software on windows laptop. And paid for forscan for iPhone about 7 quid I think, I would expect it to show you some fault codes. Get the modified code reader with the extra switch

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Thanks for the information guys. Not heard of forscan before, can I install the software on my phone/tablet or does it have to be a laptop?

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15 minutes ago, isetta said:

Being the owner of obd code reader from tunnelrat electronics (their advertised price includes uk postage) and free forscan software on windows laptop. And paid for forscan for iPhone about 7 quid I think, I would expect it to show you some fault codes. Get the modified code reader with the extra switch

Ive just googled this. Do you have the ELM327? It looks like there is a USB version and a wifi version. Is it the USB version you recommend? It has a "HS-MS CAN Switch" whatever that is 🤔

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Yes, you want the ELM327 with the HS-MS Can switch. The switch allows you to change between the two Can networks that Ford use. Some modules in the car are on the HS CAN and others are on the MS-CAN. The Tunnelrat version is highly recommended, it's not worth trying to save a few quid on a cheap version that might not work. Get the USB version if running Forscan on a Windows laptop or the WiFi version if running Forscan on an iPhone. The windows version of Forscan has more features than the iPhone version.

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Thank you very much, I really appreciate the information. Ive ordered the USB version and I will see how I get on 👍

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Ok I got my new gadget today, the USB version of the modified ELM327. It works brilliantly and I could not be more pleased with it. However, I now have more DTC codes than I know what to do with! C003A, C0037, U0401.... and the ist goes on. Its not easy deciphering which wheel I need to take off and examine as there are codes relating to multiple wheels and they cant all be broken?

New question is this: Is it possible to gather data from the wheel speed sensors using the forscan software? If so, im pretty sure that one of them will return some bogus data and I can focus my attention there.

Any help on the subject would be appreciated before I start taking things to bits 😆

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C0037 is left rear wheel speed sensor fault.

C003A is right rear wheel speed sensor fault.

U0401 is Invalid Data Received From ECM/PCM "A"

I'd say these point to a duff ABS module.

Sent from my SM-G965F using Tapatalk

 

 

 

 

 

 

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I would delete all the dtcs, go for a drive and then read the codes again. It may narrow down where the issue is. 

But with all those dtcs , it could be the abs module as Clive ( stoney) says 

Forscan can monitor all wheel speed sensors while you drive and give the speed of each wheel. But I would get another person to monitor forscan while you drive

Have you had any work done on the rear brakes or rear wheel bearings recently? 

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As Ian’s says, clear the codes. Some codes could be very old. It’s a shame the system does not provide dates for the codes. Eg. If a while back a car had a dieing battery that has since been fixed, it could still hold loads of codes which were caused by low voltage to sensors and not real faults

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Thanks guys, the other codes are: U2101, U3003, C0020 and C0082. How exactly do you delete the codes and how do you go about gathering data from the wheel speed sensors?

I found a video on you tube about a ford fusion which had a similar list of DTCs that all appeared at once. The mechanic filming the video said he read/saw a ford special service message which directed him straight to the problem. It turned out to be a damaged wire in the ABS sensor harness, a tiny little hole causing all those faults! If i knew which wheel was the problem i could examine it thoroughly. The mechanic on the fusion produced a graph of all four wheel speed sensors and one of them looked very different to the other three.

I will definitely clear the codes (once i know how) and then take it for a spin, sounds like a good plan. But if I could also get that wheel speed data I think that would help.

Once again, thank you for your input 👍

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On 6/17/2019 at 7:54 PM, iantt said:

I would delete all the dtcs, go for a drive and then read the codes again. It may narrow down where the issue is. 

But with all those dtcs , it could be the abs module as Clive ( stoney) says 

Forscan can monitor all wheel speed sensors while you drive and give the speed of each wheel. But I would get another person to monitor forscan while you drive

Have you had any work done on the rear brakes or rear wheel bearings recently? 

I have had a new caliper fitted to the driver side rear not long ago. The ABS light must have come on about 2 weeks later 🤔

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Have a quick look at the O/S/R and make sure nothing is hanging / loose, just to ensure that they've not forgotten to install the sensor wire... 😛

The data will lead you in the correct direction, "South Main Auto" on Youtube has some fantastic electronic diagnostic videos for hunting down suspected electrical problems using logic and basic knowledge.

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i cant remember exactly how to clear the codes using forscan. I know I always have a bit of trouble working it out. I think it's something to do with the icons along bottom of screen towards left edge of screen.  It might call it Reset as opposed to Clear.

 

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