97 STS, Down to 5 codes, need help please!

[burtreynolds74]

First, let me say thank you to all you guys.. this forum is awesome. I bought a 97 STS, after I crashed my Camaro; didn't really know a lot about them until I bought one, thought I would only keep it over the winter but have fallen in love with the car. So now I am determined to get it running like a champ, I'm paying off student loans so don't have the money to get it fixed at the dealer, I have average mechanical skills but thanks to this forum the car is running better than when I bought it.

I purchased it with 140K on it, the car runs strong overall but has suspension issues and some codes. Thanks to this forum, about a month ago I found out how to check the codes, at the time it had 14 codes. By researching the site, I have eliminated 9 of the 14 codes.Car came with no service history, but here is what I know:
s/s fuel recall done, owner replaced the shocks and the plug wires.
I replaced: Air Filter, Fuel Filter, Fuel Regulator, Cleaned the throttle body, recharged the A/C, installed IPAQ ipod connector (lets u control ipod w/ steering wheel controls.. pretty sweet), and new tires.

***Interesting note, in the spare tire area I found I believe to be a PCM unit. It appears owner purchased it from used parts retailer, and is in good shape. Leads me to believe it is connected to some of my problems. I assume it is worth putting in the new one, I read it plugs in but I must transfer something from the old one to the new one, any advice?

This is a long post, but if you can help w/ even one of the problems I am forever grateful. Okay, so now my problem and brief history:

PROBLEM #1: 3 RECURRENT CODES
B2120 Lumbar Up/Down Sensor Failed, CURRENT MSM
C1295 Brake Lamp Switch Circuit Open TCS
U1301 Class 2 Short to Battery SDM

PROBLEM #2: 3 NEW CODES
P0603 Control Module Long Term Memory Reset PZM
U1255 CLASS 2 COMMUNICATIONS ERRROR MSM

Sorry for all the info but I figure if you have all the information, you might be able to help. Here is a list of my codes by date:

*CODES CHECKED 3 DIFF. DATES, RESET EACH TIME*

DATE: 7/14/2009 (TEST #3, MY CURRENT CODES)
U1064 Loss of Communications with DIM
U1300 Class 2 Short to Ground
P0603 Control Module Long Term Memory Reset
P1599 ENGINE STALL DETECTED ( I ran out of gas)
U1255 CLASS 2 COMMUNICATIONS ERRROR
U1301 Class 2 Short to Battery

DATE: 7-9-09 (TEST #2)
U1300 Class 2 Short to Ground
P0603 Control Module Long Term Memory Reset
P1599 ENGINE STALL DETECTED ( I ran out of gas)
U1255 CLASS 2 COMMUNICATIONS ERRROR
U1301 Class 2 Short to Battery

DATE: 6-19-09 (TEST #1)
B0856 Battery 2 Out of Range
B1552 Keep Alive Memory (KAM) Error
B1558 BCM EPROM Checksum Error
B1656 EEPROM Write Error
B1982 Device Power Circuit High
B1983 Device Power Circuit Low
B2119 Lumbar Forward/Aft Sensor Failed
B2120 Lumbar Up/Down Sensor Failed, CURRENT
C1255 EBCM Internal Malfunction
C1295 Brake Lamp Switch Circuit Open
C1298 PCM Class 2 Serial Data Link Malfunction
U1064 U1064 Loss of Communications with DIM
U1300 Class 2 Short to Ground
U1301 Class 2 Short to Battery

If you read this far I sincerely appreciate it . In conclusion, I am sorry for the length of this post but If anyone can give me any helpful hints on what to do with the recurrent codes or thenew ones, please let me know. Any advice on the codes, pcm unit, additional maintenance you recommend on this high mileage N* that I have not done. Thanks again, and this site kicks ass.

[Ranger]

C1295 Brake Lamp Switch Circuit Open TCS
This should be the switch up on the brake pedal arm. I'd replace it.

P0603 Control Module Long Term Memory Reset PZM
U1255 CLASS 2 COMMUNICATIONS ERROR MSM
These might be from pulling battery power. Done that lately?

[burtreynolds74]

Thanks for the reply, I did disconnect the battery...... that would be great if that was all it was. I will have to check out the brake arm, but I am unfamiliar with the part... where would it be located? Thanks!

[N*Caddy]

The brake switch is located (as Ranger said) up on the brake pedal. That circuit starts with the Brake fuse (20 A engine compartment fuse center), and the brake switch. There is an input on the EBTCM module that is connected after the break switch. That's how the module knows the brakes are ON and also that's how the code is set (deceleration detected but the brake input is low).
The other things I would worry about is the plenitude of network codes you got:
U1301 Class 2 Short to Battery
U1300 Class 2 Short to Ground
U1255 CLASS 2 COMMUNICATIONS ERRROR
U1064 Loss of Communications with DIM
C1298 PCM Class 2 Serial Data Link Malfunction
This denotes that one of the modules connected to the car network has a problem. I would start with disconnecting one by one and see if the issue returns. Unfortunately if a module issue a code, it means that module is the one detecting the problem not necessarily that module is the problem.
The other concerning code is:
P1599 ENGINE STALL DETECTED ( I ran out of gas)
Please don't do that again, try keeping at least 1/4 of a tank of gas (I always fill up when half way, but that's just me). The gas is used as a coolant agent for the fuel pump. If you are low in gas the pump is not cooled properly. Trust me you don't want to change the fuel pump in your car, is expensive and labor intensive. The fuel tank needs to be dropper, then your filler neck might not be in such a good shape and once disturbed...another $500 for a new one (if you can find one because GM discontinued the part). Running with the full or almost empty tank makes no difference in the how much you pay for gas (in the end you still use the same amount).

[burtreynolds74]

Thanks a lot for your response, I was hoping you would see my post, I swear you have single handly answered half the threads questions on the site. Yesterday I went through the fuses in the engine bay, the prev ownser had removed the fuse boxes underside cover w/o me realizing it and all the fuses were shockingly dirt crusted and oxidizded.

Went through and replaced the fuses that needed it and cleaned once that were savable. Drove two hours to a job interview and came back with no module related codes... I am praying I fixed it; but I know its probably false hope.

The brake thing is really interesting though, I thought I was imaging it before but maybe what your saying is causing it. Now and then the car feels like it is slowing down very quicly w/ out me pushing on the brakes, and once and awhile it feels like I am driving the car w/ the brakes still lightly depressed and is dragging it down. Is the aforementioned problem even possible? or am I going crazy?

[Ranger]

Yes it is possible. Pull the calipers and check the pins that the caliper slides on. If the grease has dried out, the pins might be rusty thus not releasing brake pressure.