BA light appeared in dash twice, and went off. Can't find what it is in the manual

[Lpgc]

Hope you're right

Hope so for you mate.

 

[Elgraman]

Hope so for you mate.

It's a got a couple of months warranty left anyway, but of course no one wants the hassle.

 

[Tim C]

It seems users ^ in the thread have experienced it in heavy rain, which is what I was driving in (very heavy). So fingers crossed that's why is came on, went off, came back on again, and went off.
It's always paranoia time getting a used car with miles on it, not knowing what is what, and if it does something you haven't seen before the panic gates open.

It's linked to the wipers. If it's raining the radar knows, and the BA light will come on when you activate the wipers. I had 5 years of it before the cruise control broke and my BA light comes on all the time.

 

[Elgraman]

It's linked to the wipers. If it's raining the radar knows, and the BA light will come on when you activate the wipers. I had 5 years of it before the cruise control broke and my BA light comes on all the time.

I've had wipers on before though, and nothing came on. Albeit not pounding monsoon stuff like today.

 

[Elgraman]

It's linked to the wipers. If it's raining the radar knows, and the BA light will come on when you activate the wipers. I had 5 years of it before the cruise control broke and my BA light comes on all the time.

Did you used to use your Cruise, or did you never use it, and all of a sudden in broke one day out of nowhere?

 

[Tim C]

Did you used to use your Cruise, or did you never use it, and all of a sudden in broke one day out of nowhere?

Honestly, as I said, irs not broken. It's what CC fitted cars do in heavy rain. It's got nothing to do with if you have cruise control on or not. The factory cruise control is a death trap anyway.

 

[LeStempy]

Brake assist is surely the system that senses when you emergency brake and applies extra pressure to the brakes until the ABS cuts in. Is it that the brake assist is only active when the light is on. The Vehicle Dynamic Control should help you out of a skid situation by applying the brakes to whichever wheels it decides will bring the vehicle back under control. My Volvo Had VDC and the light only came on when it was called into action by my dodgy driving.

 

[Elgraman]

Honestly, as I said, irs not broken. It's what CC fitted cars do in heavy rain. It's got nothing to do with if you have cruise control on or not. The factory cruise control is a death trap anyway.

Nice one
Yes, I've never used it on any car and all of them got it (normal, not radar). I wasn't specifically seeking it on an Elgrand, just had some criteria/red lines I wouldn't budge on (for me, a 3.5 and with the 360 camera), and then waiting trying to get a decent example with those red lines. anything extra that came with it, or what colour it was, wasn't a factor.

 

[Elgraman]

Brake assist is surely the system that senses when you emergency brake and applies extra pressure to the brakes until the ABS cuts in. Is it that the brake assist is only active when the light is on. The Vehicle Dynamic Control should help you out of a skid situation by applying the brakes to whichever wheels it decides will bring the vehicle back under control. My Volvo Had VDC and the light only came on when it was called into action by my dodgy driving.

I think this 'intelligent brake assist' is kind of 'collisional brake assist', when you got the Elgrand's cruise. More steps in to stop you hitting the car in front, rather than 'helping' you when you're braking. At least that's my thinking.
I used to think collisional assists on newer 'normal cars' were invented for the mobile phone heads, with their head bopping up and down, and it steps in when they are about to rear end the car in front.

 

[Lpgc]

Honestly, as I said, irs not broken. It's what CC fitted cars do in heavy rain. It's got nothing to do with if you have cruise control on or not. The factory cruise control is a death trap anyway.

I wouldn't say the factory cruise control is a death trap, I quite like it's ability to apply the brakes. On a few occasions I've put this to the test when coming off a motorway onto the slip road and downhill to a roundabout, I was covering the brakes during my tests but never once had to press the brake pedal because the system automatically did all the breaking. It can be a bit of a pain in traffic when someone overtakes and then cuts in front of you without going much faster than you because then the system will either/both back off the throttle/brake to maintain the distance between you and the car in front. But I don't find the system to be effected by traffic in different lanes. I suspect that if the system is effected by traffic in different lanes it may be due to the aim of the radar being off-centre so detecting vehicles in other lanes as being in the same lane. Don't forget that the factory cruise has 3 distance maintenance settings, the default setting seems to me to be a bit too far and causes at least the throttle to be backed off a bit if anyone overtakes and pulls back in front in a moderate distance but the 3rd distance setting is a bit better in that respect.

 

[Tim C]

I wouldn't say the factory cruise control is a death trap, I quite like it's ability to apply the brakes. On a few occasions I've put this to the test when coming off a motorway onto the slip road and downhill to a roundabout, I was covering the brakes during my tests but never once had to press the brake pedal because the system automatically did all the breaking. It can be a bit of a pain in traffic when someone overtakes and then cuts in front of you without going much faster than you because then the system will either/both back off the throttle/brake to maintain the distance between you and the car in front. But I don't find the system to be effected by traffic in different lanes. I suspect that if the system is effected by traffic in different lanes it may be due to the aim of the radar being off-centre so detecting vehicles in other lanes as being in the same lane.

Maybe your right, mine could certainly be misaligned (it has broken anyway) but mone almost killed us all when it slammed on the brakes on the motorway by detecting a car in another lane on a corner and the car behind had to take an emergency evasion to prevent going straight into me. It was really close

 

[brent hayes]

My newly acquired 2008 S3 has radar cruse control, however it only works at low speeds for a while if I go on the motorway it come up orange saying cruse control on the dash and disengages, the code read say it's faulty speed sensors do not match as it takes a couple of readings from different places, so I have stopped using it for now, I strongly suspect it is the after market MPH chip that was fitted?
Anyway my BA comes on in heavy rain when using wipers as well even though I don't use cruse control
But ok in light rain with wipers on, so in conclusion I suspect that the radar is always working weather cruse is activated or not, What do you think of my analogy?

 

[Tim C]

My newly acquired 2008 S3 has radar cruse control, however it only works at low speeds for a while if I go on the motorway it come up orange saying cruse control on the dash and disengages, the code read say it's faulty speed sensors do not match as it takes a couple of readings from different places, so I have stopped using it for now, I strongly suspect it is the after market MPH chip that was fitted?
Anyway my BA comes on in heavy rain when using wipers as well even though I don't use cruse control
But ok in light rain with wipers on, so in conclusion I suspect that the radar is always working weather cruse is activated or not, What do you think of my analogy?

Yes, the radar is used for the brake assist system, and as its old tech it doesn't work when it's raining heavily. Modern driver assistance systems use cameras.

Yes - your correct on the other point too. Your cruise control won't work in autk mode with a mph chip added. The Japanese are very big on speed limits and its baked into the system. It's getting conflicting readings and shutting off. To be honest mph chips ate bad news anyway, and often lead to lots of issues.

 

[Elgraman]

Anyway my BA comes on in heavy rain when using wipers as well even though I don't use cruse control
But ok in light rain with wipers on, so in conclusion I suspect that the radar is always working weather cruse is activated or not, What do you think of my analogy?

May well be.
Touch wood, mine has been fine since my scare at seeing BA for the first time the other week, when driving in heavy rain ^as described in the thread. However, going by what some posters said, it hasn't been 'fine' nor was it a 'scare'; it was simply doing what it was supposed to do!

 

[Lpgc]

It's getting conflicting readings and shutting off

I agree.

These are my thoughts on the problem...
The gearbox ECU transmits vehicle speed in kph on a certain 'channel' on the canbus, let's call this speed signal A on the canbus. The speed signal (A) is transmitted to the dashboard instrument cluster in kph. The instrument cluster receives the (A) signal re-transmits it on another channel, let's call this other channel speed signal B. Things like the fuel computer use speed signal B. On a standard Elgrand that doesn't have a mph chip fitted between the canbus and the instrument cluster speed signal A and speed signal B will agree. If we fit a mph chip speed signal A will be (the conversion ratio between kph and mph which is 1.60934 times higher than signal B. On a lot of Elgrands, even those without factory cruise control, a difference between the value of A and B will cause an error code in the engine ECU but won't turn on the MIL light or (at least in itself) cause any problem. But on an Elgrand with factory cruise I expect the error code will cause the further error generated by the cruise control system that sees the cruise control disabled.

At one time I didn't believe that people's fuel computers would start to work in miles per litre (instead of the usual kilometres per litre) just because a kph to mph chip / gizmo was fitted between the canbus and the instrument cluster. Then I started noting the P1*** (I forget the exact error number) which points to a discrepancy between 2 speed signals, then I put 2 and 2 together and realised what was going on. This explains both the fuel computer reading in miles per kilometer and the factory cruise control system not working properly when such kph to mph chip / gizmo is fitted.

Thankfully when such kph to mph chip is fitted the drivertrain (transmission) still changes gear at the usual points, which says the transmission only uses speed signal A, which we'd expect anyway since all speed signals originate from the transmission. If that wasn't true (if the transmission used speed signal B) then we'd find that the gearbox wouldn't change up gear at light throttle positions unless the engine was revving faster than it'd usually be revving for a light throttle gear upchange.

But no thanks to some kph to mph chips / gizmos for causing an even wider variety of problems. No problems at all on some Elgrands. No practical problems on others (just a latent error code pointing to A<>B which causes no other issues)... To mediocre problems such as the instrument cluster not working properly, to more major problems such as the gearbox not wanting to change gear or even the engine not running properly, even not reading the crank sensor properly.

I wouldn't want a kph to mph chip fitted on any of my Elgrands. But I don't like the speedo scale being in kph either. So to me the best all round is to fit Lockwood dials, which doesn't effect any of the electronics and gives me accurate readings (and speedo reading in mph) on the instrument cluster and the odometer still reads in kilometers (so when selling the car I don't have to say it was X reading before the change to mph and now it's Y reading so we can do the maths to see how far the car has travelled since it was built). The fuel computer still works in kph to litre unless a kph to mph chip / gizmo is fitted but with a kph to mph chip fitted it still only works in miles per litre, which still isn't mpg.

 

[brent hayes]

I agree.

These are my thoughts on the problem...
The gearbox ECU transmits vehicle speed in kph on a certain 'channel' on the canbus, let's call this speed signal A on the canbus. The speed signal (A) is transmitted to the dashboard instrument cluster in kph. The instrument cluster receives the (A) signal re-transmits it on another channel, let's call this other channel speed signal B. Things like the fuel computer use speed signal B. On a standard Elgrand that doesn't have a mph chip fitted between the canbus and the instrument cluster speed signal A and speed signal B will agree. If we fit a mph chip speed signal A will be (the conversion ratio between kph and mph which is 1.60934 times higher than signal B. On a lot of Elgrands, even those without factory cruise control, a difference between the value of A and B will cause an error code in the engine ECU but won't turn on the MIL light or (at least in itself) cause any problem. But on an Elgrand with factory cruise I expect the error code will cause the further error generated by the cruise control system that sees the cruise control disabled.

At one time I didn't believe that people's fuel computers would start to work in miles per litre (instead of the usual kilometres per litre) just because a kph to mph chip / gizmo was fitted between the canbus and the instrument cluster. Then I started noting the P1*** (I forget the exact error number) which points to a discrepancy between 2 speed signals, then I put 2 and 2 together and realised what was going on. This explains both the fuel computer reading in miles per kilometer and the factory cruise control system not working properly when such kph to mph chip / gizmo is fitted.

Thankfully when such kph to mph chip is fitted the drivertrain (transmission) still changes gear at the usual points, which says the transmission only uses speed signal A, which we'd expect anyway since all speed signals originate from the transmission. If that wasn't true (if the transmission used speed signal B) then we'd find that the gearbox wouldn't change up gear at light throttle positions unless the engine was revving faster than it'd usually be revving for a light throttle gear upchange.

But no thanks to some kph to mph chips / gizmos for causing an even wider variety of problems. No problems at all on some Elgrands. No practical problems on others (just a latent error code pointing to A<>B which causes no other issues)... To mediocre problems such as the instrument cluster not working properly, to more major problems such as the gearbox not wanting to change gear or even the engine not running properly, even not reading the crank sensor properly.

I wouldn't want a kph to mph chip fitted on any of my Elgrands. But I don't like the speedo scale being in kph either. So to me the best all round is to fit Lockwood dials, which doesn't effect any of the electronics and gives me accurate readings (and speedo reading in mph) on the instrument cluster and the odometer still reads in kilometers (so when selling the car I don't have to say it was X reading before the change to mph and now it's Yw reading so we can do the maths to see how far the car has travelled since it was built). The fuel computer still works in kph to litre unless a kph to mph chip / gizmo is fitted but with a kph to mph chip fitted it still only works in miles per litre, which still isn't mpg.

Thanks for this well put together reply, most helpful.
I also thought it may be getting a speed signal from the ABS sensor as well as the speed output sensor in the back of the transmission like my old E51 2002 rwd.
Not sure if this 4 wheel drive transmission has the rear speed output sensor?

 

[Lpgc]

Thanks for this well put together reply, most helpful.
I also thought it may be getting a speed signal from the ABS sensor as well as the speed output sensor in the back of the transmission like my old E51 2002 rwd.
Not sure if this 4 wheel drive transmission has the rear speed output sensor?

You could be right on the other speed signal coming from the ABS sensors.

I've seen the 'behind the scenes' (because it doesn't cause the MIL light to come on or cause any other issues besides the cruise control problem) on 2wd Elgrands so I don't think the other signal comes from the 4x4 transfer box.

Not Elgrand related - I spent some time yesterday changing an ABS sensor reluctor ring on the NSR driveshaft of my son's BMW 3 series. He's been having problems with the ABS not working, but even more of a pain also problems with the traction control backing off the throttle at random times due to the NSR ABS sensor working intermittently and sometimes giving wildly incorrect speed signal. Not the most difficult job to change the reluctor ring but does involve taking the driveshaft completely off the car, which means first lowering the rear section of exhaust. We expected the drive shaft to be stuck on the splines in the hub, and last week when we tried to shift the shaft on it's splines it was indeed seized, so at that point we applied some ATF to the splines and yesterday the ATF seemed to have done the trick and unseized the splines. Loads of rust on the old reluctor ring and in that general area on the driveshaft so we cleaned it all up before fitting the new ring. The new ring was supposed to be an interference fit but was a bit looser than that, it came supplied with some anaerobic glue to stick the ring in place on the driveshaft but the glue is only designed to help further secure an interference fit, so we also added a bit of superglue lol. He's still having the same problems so the real issue must be the sensor but he only changed the sensor 12 months ago and it was his idea we change the reluctor ring and cleared the rust up thinking that'd more likely be the problem than the sensor. I think it was still a good call to change the ring even though we also need to change the sensor (again).

 

[brent hayes]

I

You could be right on the other speed signal coming from the ABS sensors.

I've seen the 'behind the scenes' (because it doesn't cause the MIL light to come on or cause any other issues besides the cruise control problem) on 2wd Elgrands so I don't think the other signal comes from the 4x4 transfer box.

I did some research on the jatco transmission and have in-depth schematics of all veriants of the rear wheel drive version with all facts n figures along with videos of how to rebuild and kits you can install to make them shift faster, but nothing on the four wheel drive, so more research required lol.

 

[brent hayes]

You could be right on the other speed signal coming from the ABS sensors.

I've seen the 'behind the scenes' (because it doesn't cause the MIL light to come on or cause any other issues besides the cruise control problem) on 2wd Elgrands so I don't think the other signal comes from the 4x4 transfer box.

Not Elgrand related - I spent some time yesterday changing an ABS sensor reluctor ring on the NSR driveshaft of my son's BMW 3 series. He's been having problems with the ABS not working, but even more of a pain also problems with the traction control backing off the throttle at random times due to the NSR ABS sensor working intermittently and sometimes giving wildly incorrect speed signal. Not the most difficult job to change the reluctor ring but does involve taking the driveshaft completely off the car, which means first lowering the rear section of exhaust. We expected the drive shaft to be stuck on the splines in the hub, and last week when we tried to shift the shaft on it's splines it was indeed seized, so at that point we applied some ATF to the splines and yesterday the ATF seemed to have done the trick and unseized the splines. Loads of rust on the old reluctor ring and in that general area on the driveshaft so we cleaned it all up before fitting the new ring. The new ring was supposed to be an interference fit but was a bit looser than that, it came supplied with some anaerobic glue to stick the ring in place on the driveshaft but the glue is only designed to help further secure an interference fit, so we also added a bit of superglue lol. He's still having the same problems so the real issue must be the sensor but he only changed the sensor 12 months ago and it was his idea we change the reluctor ring and cleared the rust up thinking that'd more likely be the problem than the sensor. I think it was still a good call to change the ring even though we also need to change the sensor (again).

Very good, may I suggest a 70% transmission fluid and 30% acetone mix , better penatrent than anything you can buy?

 

[wombat]

Ive got a e51 Elgrand with radar control braking the ba light has been on for 2 years ive never been able to get rid of it I cant use cruise control but doesnt affect any other operation.cant find any other option to get rid tried ecu codes says no error codes may give up now