BAS/ASR question.

[John Jones Jr.]

Does anybody know if there's a fault with the BAS and it stops operating, can the ASR still operate or are they totally integrated?

[RemoLexi]

Pretty sure it's one module. Not sure if one fault will cause the other feature to quit working. This maybe one of those questions that MB won't release the answer to.

People ask all the time- 'if my srs light is on for a reason like the occupancy sensor failure, will my airbags still deploy during collision'? ... No automaker will answer that for legality reasons, now, who wants to test the airbags in order to answer that? Doubt anyone does!

[John Jones Jr.]

Yes, Remo it seems to be the one module (mounted just below the brake booster) and the BAS sensor/valve is mounted to the booster. And this is one of the reasons why I wondering if the ASR would be affected as the BAS sensor is independent of the ASR by virtue of it being separate. Of course an easy way to tell if the ASR will still operate when the the BAS is faulty is simply to get the ASR to activate on rough roads, gravel etc. In my case when the BAS/ASR warning light illuminates with is very often, neither work.

The main reason I'm asking is because I think I've a Throttle Body problem (stumble at idle and flat spots) and I suspect it could affect the operation of both the BAS & ASR, depending what's wrong with the T/b. Really, I'm just looking for hints that might point to the T/B being the problem as there's no fault codes present even on STAR except for the BAS fault and it's indicating that the booster sensor is possibly faulty.

[AMG KC]

You sure your MAF is not out of spec?

[RemoLexi]

You could be onto something!

What year/ model is yours? I have a few tb's lying around

[John Jones Jr.]

Cheers for the offer Remo but as I'm either in Ireland or the U.K. it would not be cost effective to get a used one from the States between shipping and customs duty parts can turn out rather expensive even excluding the purchase price. Also, there is a few companies that recon them this side of the pond and the cost is reasonable from what I've been told. But if I do get stuck, I'll get in touch, thanks again.

[John Jones Jr.]

You sure your MAF is not out of spec?

AMG KC, you could be dead right and I do actually have a MAF problem along with a BAS fault too and there's nothing wrong with the T/b. I just wish the problem got worse, then I might get some fault code to indicate the where the problem is. I'll update when I've got any news.

[AMG KC]

Well you never know, cause what youve described is basically what i had with my car when i bought it. It didnt really seem to be getting worse either, it was quite consistant, the car ran reasonably well.

When cold, it would not hessitate in the usual sense, but when i floored it, there was a long run up til all of a sudden you got a boot in the arse around 4,000rpm.

When warmed up, standing starts at WOT would occationally allow the engine to hit the rev limiter in first prior to shifting. Shifting often seemed abit erratic too, it wasnt always predictable, and often seemed as though there was a longer than usual closed throttle between shifts.

It might just be worth looking into that, a genuine MAF is pretty cheap!!

[John Jones Jr.]

Yep, I think a new MAF is worth a shot before I do anything else, it also won't be any harm to have spare one even, if it's not the problem now.

[RemoLexi]

I'm sure you have cleaned the throttle body correct?

[AMG KC]

Its a pain in the arse to get to it!!

[John Jones Jr.]

I'm sure you have cleaned the throttle body correct?

Yeah, I did and it's spotless now, not that it was dirty in the first place. Also opened up the T/b, checked the carbon tracks & contacts (no excessive wear), cleaned them too.

[John Jones Jr.]

Its a pain in the arse to get to it!!

They're handy aren't they, all of ten minutes to remove & open up.

[AMG KC]

I used to have two C4 Corvettes, mostly very easy to work on... Til you convert them to right hand drive and put big tri-y headers on there... Then spark plugs become a two hour jobs.

I just did the rear brake pads on my C180 in 20 minutes from start to all packed up, on gravel!! Some jobs are just really easy on these cars ;)

Keep us posted on that new MAF when you get to it, im keen to hear if it fixes the issue :)

[John Jones Jr.]

Til you convert them to right hand drive


Where in the world are you?

[AMG KC]

Australia.

[John Jones Jr.]

Ah, I was wondering.

[AMG KC]

Most states here require the car the be right hand drive until it is over a certain age, usually 30 years.

[John Jones Jr.]

BAS issue resolved. Brake light switch replaced (fault showed up on STAR) along with a used BAS control module fitted. When those two items were sorted at the same time the throttle adaptations were carried out (again using STAR) so I'm actually not too sure it needed the BAS module. Anyway, it's sorted that's the main thing.

[Vetruck]

Big relief. Problems like this can be frustrating. Good job.

[John Jones Jr.]

Yeah Dean, I really hate electronic issues like that. Partly because I'm helpless unless I get lucky working out the exact cause of the problem or visit a Merc specialist and put myself at their mercy. I have to say it's nice all the same having the BAS back working even if I only had cause to use it once prior to it failing.