stick152

I'm new to the forum, but have benefited from some of the posts and wanted to give something back; I wanted to pass on my experience fixing some of the persistent DTCs I've had on my baby. I have a 2003 with just under 80K on it (my first vette!). I got it in Feb. of this year (2010) with 78K on it and it's been relatively problem free - had to have the crank shaft balancer replaced (under warranty) due to a nasty wobble. Other than that, awesome! Until... I started getting intermittent Traction Control / Active Handling messages. I also have had some HVAC DTCs since I bought the car - I cleared all the codes when I got the car home (found a post here telling me how) and these (the TCS and HVAC codes) where the only ones to come back.

The codes were as follows:
TCS: C1287 Steering Sensor Rate Malfunction

HVAC:
B0361 H Left Actuator Feedback Short to GND
B0441 H Left Actuator Out of Range

Just from readin the TCS code, and from some posts that I found on the web, I though that I was looking at replacing the SWPS. Not too bad of a job, and it runs $79.99 (or so) at Autozone so not too terribly expensive. I always like to do my research on these kinds of problems, so I kept digging and came across Bill Curlee's "Important Electrical Information" post (http://forums.corvetteforum.com/c5-t...tion-long.html). I checked out G101 and G102 and, lo and behold, there was about two pounds of corrosion / sand inside! After thoroughly cleaning those two ground points, plus the ground next to the battery, the TCS DTC is gone. I was getting it about once a week, even sitting still at stop lights, but I haven't seen it in almost a month! Thanks Bill!!!

Next, it was on to the HVAC DTCs. I did a lot of digging on the forum (and elsewhere on the web) and came to the conclusion that it was the actuator - pretty likely given the codes, right? I pulled the entire dash pad and driver-side knee panel (not too bad actually, the whole removal only took about 45 minutes) and set to work seeing what was actually wrong before I went and dropped the $150 (including tax) on an actuator. Looking at the blend doors (the white, hard plastic flaps that get moved by the actuator), the driver-side door wouldn't go down all the way (i.e., it wouldn't seat itself all the way against the bottom stop - it was 1/2 an inch or more from the bottom stop) while the right one would go full travel. I pulled out the actuator and moved the door manually; it moved full travel. So I took apart the actuator - mine was one of the newer style ones that clip together, so I couldn't just re-index it (I tried though, but to no avail). I didn't see anything glaringly obvious inside that would prevent it from moving full travel, so I bit the bullet and bought the new actuator.

I installed the new actuator, pulled the HVAC fuse (#27?) for several minutes while I went and got some water, put the fuse back in, turned the key to "on" position, listened for the HVAC system to do its thing, checked for DTCs and they were still there. So I cleared them, which caused the HVAC system to do its test again, and the codes came back. Sure enough, even with the new actuator, the driver-side blend door wasn't moving full travel during the self-test (the passenger side was). I tried disconnecting the battery for 10 minutes and checked codes again; kept popping back up. I started the car and, while running the AC and adjusting the dual climate settings, watched the blend doors on both sides. As I adjusted the passenger-side air temp, the passenger side blend door would move through its full travel (from top stop to bottom stop as near as I could tell), but the driver side would stop about 1/2 inch or more before reaching the bottom stop.

At this point, the expletives were flying. I was unable to find anything blocking the driver-side blend door (as I said above, it traveled full throw by hand) and was starting to get frustrated. I thought about it for a while and had an epiphany; swap the driver and passenger actuators and see if the codes change to reflect the passenger side. I figured why not, I've tried everything else? So I did... The freakin' door moved full travel during the "self-test" and the #$%^ codes went away! Being the glutton for punishment that I apparently am, I wanted to make sure that the fix was for real and not just a glitch. So, I swapped the actuators back, pulled the negative battery lead for another 10 minutes, then ran the self-test again; the codes came back on the driver side. I pulled the negative battery lead, re-did the swap, let the HVAC system do its thing and no more codes! With the AC running, I watched the blend doors while I adjusted the dual-zone control; both moved properly and the driver-side actually went all the way to its stops in both directions (as near as I could tell by feel).

I test software and hardware for a living and I generally like to know WHY a fix works; I have some ideas why it might work, but nothing definitive. I'm counting my blessings that it DID work, but I'm wondering now if the new actuator was actually necessary. If anyone else out there with one of the newer-style actuators gets these codes, you might try swapping sides on the actuators to see if it fixes your problem. Just to note, I checked the part numbers for the two original actuators and they are identical; there's apparently not a specific driver-side and/or passenger-side actuator.

After getting this all buttoned up, guess what? ANOTHER FREAKIN' DTC!!!! This time it was C1295 Brake Lamp Switch Circuit Open. As seen in other posts, it only came on when I used the hazard lights, and then only if the brake wasn't pressed. I dug around on the forum and found all kinds of good info to check. I asked my daughter to check if all my brake lights were working, and she said that the center light was NOT. So, I pulled off one of the inner brake lights and checked the plug for the center light (expecting to find some corrosion or something); it was completely unplugged! Not sure how the plug fell out, or when, but it had. Plugged the light back in and no more code!

At any rate, I hope this isn't too wordy for all of you and that it might give someone else ideas on fixing these same DTCs.

Shawn

wcsinx

A new actuator was probably not necessary in your situation. Did you take the old one apart and look inside it? Unless it had a broken or stripped gear, then there was no reason to replace it. The thing is, you get those codes because the mixer door warps or the seals collapse or w/e. Hence the source of the problem isn't actually the actuator itself. When people take the actuators apart and reindex the gears, what they're doing in effect is fooling the computer into closing the door a tad farther/harder. I had to do this fix on my '02 even though it supposedly has a revised headunit firmware that allows for a greater tolerance of the sweep values.

stick152

I did take the old one apart. It's one of the newer-style ones with the stops on the cap. There are two copper(?) tabs on the bottom of the primary gear (the one that attaches to the shaft going to the blend door) that run along two parallel traces and appear to be making an electrical contact. The tabs and traces all looked to be in serviceable shape. There also weren't any bad teeth on any of the gears and all of them moved freely. I spent the better part of an hour trying to see if re-indexing the gear would help - it didn't. I didn't understand the system enough to know what else could be wrong, so I just went ahead and got the new actuator with the idea that there might be something wrong that I just couldn't see. I just wish I'd thought to swap sides before I'd bought the new actuator. I've had more expensive lessons, but still, $150...

Boulty1961

Sometimes you don't have a choice.
You have to buy a new part.
I was going to reindex mine but this is what I found.
The gear is cracked in two places.
Hello GMPartsHouse..........

dspiroff

What is the best way to access the actuators? Is there a step procedure or pictural gide to accessing? Your article was excellent I will also check the two ground locations you menmtioned.

Boulty1961

http://vette.tnreeds.com/actuator/actuator.htm

I think this is the GM part number 89018365
I got mine from www.gmpartshouse.com
Gene is always good to answer questions to help you get the correct part you need.