TSB-07-05-25-007B Calibration Letter

[Bogie]

Originally Posted by TINOONIT

NHTSA get on this fix NOW!

The case is closed. NHTSA is done.

[TINOONIT]

a question for those of you that have had this bulletin done and it fixed the problem...

Do your brakes work immediately at cold start-up even while the car is still in high idle?????

In other words, are your brakes now working within 30 seconds of a cold start without being spongy???

[SCVanguard]

NOPE. About 9 times of 10, I can drop to low idle with a tap of the throttle and the brakes still need roughly ten seconds before they are not spongy.

[Sky_Pilot]

Originally Posted by Bogie

The case is closed. NHTSA is done.

Bogie is correct, there's nothing wrong with our brakes!

[Bogie]

Had the update completed on Saturday. I forgot to check 'em Sunday as I was on my automatic routine of letting it warm up during my prep. This morning, I forced myself NOT to start the car until all my prep was ready.

I started the vehicle and engaged reverse within five seconds. The TSB seems to have made a significant improvement in OHB response on a cold start. Not quite as responsive as vacuum; I could still feel a slight brake vibration (not a problem for me as long as the response is appropriate), and it seemed a bit more spongy than vacuum assist. But the spongy is good compared to my previous encounters which was a rock hard pedal with limited response as I rolled toward destruction. Furthermore, if I wasn't focused on feeling the difference, I'm not sure if I would have noticed a difference between the spongy, but effective, OHB response and a full vacuum response. I could also feel the transition from OHB to Vacuum, which was pleasantly smooth, compared to before where I went from trying like hell to get OHB to respond to a whiplash stop as vacuum finally kicked in. As with the initial brake application, I'm not sure if this transition would be noticeable except I was concentrating on feeling the difference.

If the response remains consistent, I would say this fix sufficiently addresses any concerns I may have on MY SKY. But to err on the side of caution, I will still test it a bunch more before handing it over to valet for an extended period of time.

For those who have had the TSB upgrade, make sure you have TSB-07-05-25-007B. It should be identified as such on your work order paperwork.

Edit: Tested again on 7/29/08. Still doing good.

[samunoz1]

I had this "upgrade" performed to little affect. Its less "spongy/crunchy", to keep inline with our nomenclature, but fact is its just plain old not right! This is the one thing that pisses me off about the car.

I can't convince the wife to let me get the Shelby Mustang GT KR. Probably has something to do with having an '08 Avalanche LTZ parked next to the '08 Sky RL. :-D

[ChgoBlues]

Question on the Field:

Of those that have received the letter for the TSB, did you have prior attempts to correct the brake concern or was this a blanket mailing to certain VINs? To date, I've still not received anything from Saturn regarding the issue.

[mbeardsley]

Originally Posted by ChgoBlues

Question on the Field:

Of those that have received the letter for the TSB, did you have prior attempts to correct the brake concern or was this a blanket mailing to certain VINs? To date, I've still not received anything from Saturn regarding the issue.

I have not had any attempts to address the brake issue (I only have a minor "crunchy" feel in the brakes at start-up), but I did receive the letter notifying me of the re-calibration.

I haven't had it done yet, but I will when I get my next oil-change, probably in about a month or so.

For reference purposes, I have a very early build '08 RL.

[samunoz1]

I had to go in to have my tail light gaskets replaced. They were letting moisture in and condense on the inside. During that time I also mentioned the brake issue and had it documented. When I picked up the car they said it was normal and that I needed to let it warm up longer.

3 months later I received the bulletin. I assume my sky is an early build since I bought it June 07.

[ChgoBlues]

Originally Posted by samunoz1

I had to go in to have my tail light gaskets replaced. They were letting moisture in and condense on the inside. During that time I also mentioned the brake issue and had it documented. When I picked up the car they said it was normal and that I needed to let it warm up longer.

3 months later I received the bulletin. I assume my sky is an early build since I bought it June 07.

Some condensation is normal in the brake lights of GM vehicles because of the way they vent. Headlights have the same issue. It's due to the difference in temps between the assembly and the ambient air temp. I remember they issued a bulletin on this just prior to my leaving the facility I worked at.

[ChgoBlues]

Originally Posted by mbeardsley

I have not had any attempts to address the brake issue (I only have a minor "crunchy" feel in the brakes at start-up), but I did receive the letter notifying me of the re-calibration.

I haven't had it done yet, but I will when I get my next oil-change, probably in about a month or so.

For reference purposes, I have a very early build '08 RL.

I also have an early build '08, built in June '07, but I haven't experienced the brake concern yet since I let the idle come down before I move. I'm usually getting my seat belt buckled, sunglasses on, etc. before I put it into gear.

[mbeardsley]

Originally Posted by samunoz1

3 months later I received the bulletin. I assume my sky is an early build since I bought it June 07.

Wow, you must have a VERY early build to have received it in June. They started building the '08s on June 18th. They must have gotten it to your dealership pretty quickly.

[Celt03]

Can somebody please post this TSB ?

The newest service tech lead at my dealership (who has no idea how to look up TSB's) says TSB-07-05-25-007B does not exist.

I have an early '08, have this problem, have not got the letter (which is no surprise since our mail is constantly screwed up)
& the dealership is really p'ing me off (one more time).

[Bogie]

I don't have the TSB, but I can confirm the number. I'm looking at my service ticket for the brake update. Here's the quote right off the ticket:

"REPROGRAMMED EBCM-ECM AS PER BULLETIN 07-05-25-007B BRAKE BOOSTER VACUUM".

At the expense of stating the obvious, make sure they know it's "B" and not an "8". And make sure they're typing zeros and not ohs.

Very happy with the results. Big improvement.

[SteveSky67]

Originally Posted by Celt03

I have an early '08, have this problem, have not got the letter (which is no surprise since our mail is constantly screwed up)

My apologies for you mail deliverly problems, guess your getting other people's mail?? I am going to PM you a solution

[Rail Jockey]

I also have an early 08 built third week of June, I haven't received it ether.
Just curious, has anyone that has had it done noticed any performance change besides the brakes good or bad.

[Bogie]

Originally Posted by Rail Jockey

I also have an early 08 built third week of June, I haven't received it ether.
Just curious, has anyone that has had it done noticed any performance change besides the brakes good or bad.

I've noticed no other performance changes other than much more responsive OHB brakes on start up.

The engineer in me is now very curious about the electro mechanical design of the brake "input" considering the system seems capable of brake deflection independent of vacuum compliance. This suggests a wee bit more linkage complexity than what one would normally encounter.

A normal brake vacuum system can basically have the mechanics hard connected to the vacuum diaphragm. When vacuum is present, the brake pedal is easy to push. When no vacuum is present, the brake pedal is hard to push.

An OHB system seems like it would need additional "gearing". I use the term "gearing" loosely to describe some kind of linkage that allows the brake pedal to drive two functions....one function being the normal vacuum initiation and the other function the OHB. The normal vacuum linkage will need to be designed to disconnect from the diaphragm on no vacuum start in order to allow the pedal to deflect. The brake pedal deflection would thus drive the OHB. Once vacuum builds, the reverse would occur. The system would need to back off the OHB function and allow the normal vacuum process to work.

The initial problems with the brakes suggest the transition to/from OHB and from/to vacuum had some programming issues. This is a very interesting process since it involves programming an electronic response (OHB), the need for which is determined by the feedback from a rapidly changing mechanical response (vacuum), when the input for BOTH responses is the same (user applied pressure on the brake pedal).

How does one use the SAME input (driver's force on the pedal) to drive two different processes (an electronic OHB and an mechanical vacuum assist), when the response of each process is dependent upon the response of the other process, which is dependent upon the driver's input on the brake pedal?

[SteveSky67]

Got my brakes done today, was in an out within 45 minutes....also, after they pulled my car out, they wanted to wash my car, all of a sudden the post the Celt03 posted about washing the car flashed in my mind, i said very nicely,
no thanks, i washed the car this past sunday and went on my way...Thanks Celt03 for posting that...

[HotRedPepper]

I had the work done to correct the braking issue about a month ago when I took my RL in for a oil change. I have noticed a difference in my startup in the morning. No need to wait as long anymore before taking off out of the driveway.