How Do I Disable ABS?

Author
Discussion

Martin43

Original Poster:

69 posts

178 months

Sunday 14th December 2014
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Evening all,

I've got an Astra H SRI (2006) and I have a problem with the ABS sensor. I can't get it in to the garage until the middle of next week so I want to disable the ABS until then.

I thought about taking out the fuse in the engine compartment (number 16) but it didn't seem to disable it?

Can anyone help?

Thanks

Martin

HTP99

22,443 posts

139 months

Sunday 14th December 2014
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Why would you want to disable it, the braking system will still work if the sensor is playing up, also if the ABS light is on then the system is disabled anyway?

PositronicRay

26,957 posts

182 months

Sunday 14th December 2014
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If you disable an ABS unit (fuse etc) it will still show a warning light, if it's the light you want out remove the bulb.

Martin43

Original Poster:

69 posts

178 months

Sunday 14th December 2014
quotequote all
Because the sensor is playing up, it's sending the wrong signals to the engine and it's causing the car to send too much or not enough fuel to the engine. Not all the time, just some of it.

HTP99

22,443 posts

139 months

Sunday 14th December 2014
quotequote all
Martin43 said:
Because the sensor is playing up, it's sending the wrong signals to the engine and it's causing the car to send too much or not enough fuel to the engine. Not all the time, just some of it.
Really, you sure there isn't a different problem, I'm pretty sure an ABS sensor measures the rotation of a wheel which would have nothing to do with the amount of fuel being pumped into the engine?

Doctor Volt

336 posts

124 months

Sunday 14th December 2014
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Martin43

This is a new one to me
Are you sure that the ECU takes a signal from a wheel sensor to adjust the fuel mixture?

I have a feeling that you have read or been given bad information

Yes there is every possibility for an ECU to require a speed signal but I doubt very much that the speed signal would be taken from one wheel - I would expect the ECU speed signal to be taken from the differential

There is something in the back of my mind telling me I have come across a vehicle or two that used ABS sensors for the speed signal but I dont think your Astra uses this method

You could have a fault that is making the Engine and ABS fail or you could have two faults

Have you checked all the ABS Sensors to be sure one is faulty?

Doctor Volt

336 posts

124 months

Sunday 14th December 2014
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HTP99

Crossed posts above - I hadnt read your post, I was typing you were posting

I agree with HTP99


blank

3,439 posts

187 months

Sunday 14th December 2014
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Sounds very strange. Have you tried turning the traction control off using the normal switch?

andyiley

9,105 posts

151 months

Monday 15th December 2014
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Really?

horza

491 posts

206 months

Monday 15th December 2014
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PositronicRay said:
If you disable an ABS unit (fuse etc) it will still show a warning light, if it's the light you want out remove the bulb.
No light is an MOT failure now. Assuming your tester notices it.


HTP99

22,443 posts

139 months

Monday 15th December 2014
quotequote all
blank said:
Sounds very strange. Have you tried turning the traction control off using the normal switch?
Traction control was one thing that I thought off, as traction control does indeed limit fuel to the engine as well as helping with braking, however it is a 2006 car; would it have TC?

stevieturbo

17,229 posts

246 months

Monday 15th December 2014
quotequote all
Doctor Volt said:
Martin43

This is a new one to me
Are you sure that the ECU takes a signal from a wheel sensor to adjust the fuel mixture?

I have a feeling that you have read or been given bad information

Yes there is every possibility for an ECU to require a speed signal but I doubt very much that the speed signal would be taken from one wheel - I would expect the ECU speed signal to be taken from the differential

There is something in the back of my mind telling me I have come across a vehicle or two that used ABS sensors for the speed signal but I dont think your Astra uses this method

You could have a fault that is making the Engine and ABS fail or you could have two faults

Have you checked all the ABS Sensors to be sure one is faulty?
Astra uses the ABS signal for the roadspeed info too, so if the ecu isnt getting a valid speed signal, it can cause a limp mode with reduced power.

The wheel bearing/speed sensors do give trouble on them. Although even cars in good order give bloody speed signal errors.

So in this case the problem isnt likely to be the ABS as such, more lack of valid speed signal.

Disabling the ABS will do nothing for you, as it is probably not the problem. ABS faults would not cause any engine related problems if they were strictly an ABS fault.

Edited by stevieturbo on Monday 15th December 20:34

Doctor Volt

336 posts

124 months

Tuesday 16th December 2014
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stevieturbo posted
Astra uses the ABS signal for the roadspeed info too, so if the ecu isnt getting a valid speed signal, it can cause a limp mode with reduced power.

This is very interesting - I have always thought that Limp Home Mode was built into the ECU's and did not rely on sensor signals to help it function

Example - The engine temperature sensor that governs how much fuel is made available to an engine for cold starting and warm running goes open circuit, should the engine be running at the time when the sensor goes open circuit the ECU will use a built-in resistance value to keep the engine running although it may cough and splutter depending on its temperature
This is very similar to going back to Home Computer Default Values when something fails to function correctly

I find it very interesting that a Motor Manufacturer when building Limp Home Mode into an ECU would rely on external sensor signals for speed signal when a vehicle goes into Limp Home Mode, surely it is much less complicated to have a built in set of default values (I use the term default values as an example due to not knowing the terminology used by different Manufacturers for get it home settings etc) that will be put into operation should any sensors fail

stevieturbo Will you kindly put me in the direction of documentation that states and explains how ABS sensors are used for speed signal to assist an Astra H SRI (2006) when in Limp Home Mode

Thank you in advance - I need to read up on the above method

stevieturbo

17,229 posts

246 months

Tuesday 16th December 2014
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Doctor Volt said:
stevieturbo posted
Astra uses the ABS signal for the roadspeed info too, so if the ecu isnt getting a valid speed signal, it can cause a limp mode with reduced power.

This is very interesting - I have always thought that Limp Home Mode was built into the ECU's and did not rely on sensor signals to help it function

Example - The engine temperature sensor that governs how much fuel is made available to an engine for cold starting and warm running goes open circuit, should the engine be running at the time when the sensor goes open circuit the ECU will use a built-in resistance value to keep the engine running although it may cough and splutter depending on its temperature
This is very similar to going back to Home Computer Default Values when something fails to function correctly

I find it very interesting that a Motor Manufacturer when building Limp Home Mode into an ECU would rely on external sensor signals for speed signal when a vehicle goes into Limp Home Mode, surely it is much less complicated to have a built in set of default values (I use the term default values as an example due to not knowing the terminology used by different Manufacturers for get it home settings etc) that will be put into operation should any sensors fail

stevieturbo Will you kindly put me in the direction of documentation that states and explains how ABS sensors are used for speed signal to assist an Astra H SRI (2006) when in Limp Home Mode

Thank you in advance - I need to read up on the above method
Every ecu relies on external sensors, so not sure what seems odd ?

As for the ecu using a dummy value, not so much. ECU's are very complex things, and stating that approach is overly simplifying what they do. A sensor certainly doesnt need to to open or short circuit for the ecu to determine something is wrong. It just needs to fall outside a certain range that it deems as normal.
And virtually every ecu in a modern car will get unhappy if there is no valid roadspeed signal.

And you're thinking too specifically of ABS here. There are wheel speed sensors which will be shared among the array of stupid ecu devices in the car, of which there are many. What each one uses these inputs for is up to them, so wheel speed sensors are not specifically ABS sensors in this case
On Vauxhalls and a lot of modern cars, there are literally dozens of modules that communicate via CAN, sharing all sorts of info, and causing equally as much trouble when something goes wrong


What specific fault codes are coming up ?

Doctor Volt

336 posts

124 months

Tuesday 16th December 2014
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stevieturbo posted

[b]Every ecu relies on external sensors, so not sure what seems odd ?

As for the ecu using a dummy value, not so much. ECU's are very complex things, and stating that approach is overly simplifying what they do. A sensor certainly doesnt need to to open or short circuit for the ecu to determine something is wrong. It just needs to fall outside a certain range that it deems as normal.
And virtually every ecu in a modern car will get unhappy if there is no valid roadspeed signal.

And you're thinking too specifically of ABS here. There are wheel speed sensors which will be shared among the array of stupid ecu devices in the car, of which there are many. What each one uses these inputs for is up to them, so wheel speed sensors are not specifically ABS sensors in this case
On Vauxhalls and a lot of modern cars, there are literally dozens of modules that communicate via CAN, sharing all sorts of info, and causing equally as much trouble when something goes wrong


What specific fault codes are coming up ?[/b]

stevieturbo I asked -

stevieturbo Will you kindly put me in the direction of documentation that states and explains how ABS sensors are used for speed signal to assist an Astra H SRI (2006) when in Limp Home Mode

Thank you in advance - I need to read up on the above method

stevieturbo I didnt ask for a lecture about Motor Vehicle Electrics from you

I take it your answer is no to my question








Mr2Mike

20,143 posts

254 months

Tuesday 16th December 2014
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Doctor Volt said:
stevieturbo I asked -

stevieturbo Will you kindly put me in the direction of documentation that states and explains how ABS sensors are used for speed signal to assist an Astra H SRI (2006) when in Limp Home Mode
Why are you asking Steve this question when he has stated nothing of the sort?

He is simply saying that some cars use ABS sensors to determine road speed, rather than a separate sensor in the gearbox. Pretty much all modern engine ECUs (as well as other control units) require a road speed signal, and the lack of this signal will flag a fault. It's not complicated, why are you making it so?

Doctor Volt

336 posts

124 months

Tuesday 16th December 2014
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stevieturbo ?

stevieturbo

17,229 posts

246 months

Tuesday 16th December 2014
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Which part of the quite simple explanation do you not understand ?

TheEnd

15,370 posts

187 months

Tuesday 16th December 2014
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The speed signal (or lack of it) doesn't help limp mode, it causes it.


Doctor Volt

336 posts

124 months

Tuesday 16th December 2014
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stevieturbo
It is best that I leave things be on the above subject

Cheers. Doctor Volt