wingnut
Nominated Tester
Posts: 186
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Post by wingnut on Sept 18, 2005 12:14:36 GMT
Had a local chap come in for an MOT, we failed it on the ABS light not illuminating. Q how long have you had the vehicle. A Three years and it has always passed. Check revealed no bulb and after checking codes a costly repair is needed. O dear and we are the only testing station apart from one close by and they like our selves have gone live. Have they refused to test some of the problem cars incorrectly passed before hand. One thing is for sure the standard will be better in time going live.
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Tom
Nominated Tester
Posts: 227
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Post by Tom on Sept 20, 2005 6:59:37 GMT
I too failed a car on ABS light recently. The customer said that it had never worked & he's had the car for 5 years!
This was the first time it came into us for MOT.
The customer tried everything to get us to pass it as it was, playing the old chestnuts: 'It was like that last year' & 'The ABS does work'.
Because there was no ABS light illuminating on the instrument panel, I think that previous testers may have not realised that the vehicle had ABS. Perhaps when the underbonnet checks were done, they may have forgotten that they had not checked the ABS light... Or they knew the light wasn't working but couldn't be bothered to issue a fail... What do you think ??
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wingnut
Nominated Tester
Posts: 186
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Post by wingnut on Sept 20, 2005 12:49:29 GMT
Ho Hum,no way in last three years could it be overlooked. Abs wall chart as a guide first for light details. Then the old check list "system and controls under bonnet checks" Master cylinder brake pipes etc would show if ABS fitted every tester should know the difference. Under side checks would show the sensors and on this vehicle there were four. Testing of ABS systems working is paramount as some braking systems over time stop working safely on braking.
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graham
Nominated Tester
Posts: 331
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Post by graham on Sept 20, 2005 17:52:43 GMT
But isn't the problem that you do the interior checks and a none working bulb does not exactly "shine out at you". It is easy to forget that an ABS warning light didn't light up when you are checking under bonnet later on. Hell we have enough to remember when doing a test with all the date cut off points, checking for mixed tyre sizes, seat belt permutations etc.
Well the only one I can think of is the Ford with the Teeves system and if they fail you know BIG time cos you have no servo action and it takes super human pressure to stop the vehicle. All others "fail safe" to normal braking.
Graham
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wingnut
Nominated Tester
Posts: 186
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Post by wingnut on Sept 20, 2005 19:57:23 GMT
Useing the assistant to do the operation of the controls when the tester is doing under bonnet checks we have got into the habbit of checking the ABS light when ABS is fitted as well as the initial check,with the tester useing the check list as he go's. Graham i did say "some" on the brakes not all.
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graham
Nominated Tester
Posts: 331
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Post by graham on Sept 20, 2005 20:58:31 GMT
Graham i did say "some" on the brakes not all. No problem, I did see that part. Just that the only car I can think of that an ABS fault would affect the brakes is that particular Teeves system mainly used by Ford. In theory ABS should default to standard braking if a fault develops[1] so in effect braking efficiency is the same. The aim of ABS isn't to reduce stopping distance but to increase "steerability" under hard/locking braking. Personally I would sooner see airbag lights included than ABS Graham [1] A possible wireing fault on some vehicles, where the ECU is remote from the solenoid valves, could cause a caliper/wheel cylinder not to receive pressurised fluid - result would be VERY unbalanced brakes....
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wingnut
Nominated Tester
Posts: 186
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Post by wingnut on Sept 21, 2005 9:34:26 GMT
Graham. just to say without going into to many contributary facts,all types fitted with the high pressure pump when it fails and the types with the back up sphere when nitrogen depletes still have braking but not safe. Ie heavy pedal, as the old farmer in Wales found out towing a water bowser with Range Rover on hilly ground when the whole outfit got away with frightening results. The air bag if fitted would not help him. No brakes first then air bag testing maybe later.
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