Mechanics

I/P TELLTALE & MIL LIGHTS

2001 Saturn L300

Computer problem
2001 Saturn L300 6 cyl Two Wheel Drive Automatic 134000 miles

ABS, SRS, & service(wrench) are on. No DTC's stored or pending. Reset service light, come right back on. No drivability problems or obvious malfunctions (except 1 will explain) ABS seems to be performing properly, can not get brakes to lock up. SRS light performs 7 flash check in when ignition is turned on, then stay's on. SRS system has never been deployed. Nothing appears to have ever been tampered with. Fuses & circuts are all ok. Gauges all work. Only 2 clues I have so far, 1. While driving with A/C on the blower will suddenly cut out for about 5-7 seconds then come back on. 2. Speakers in rear doors do not work. I have been a mechanic for 20 years & I am very familuar with the OBD2 comp systems. Have investigated every possible cause from power dist. To ground distribution. The only thing left I cant do on my own is hook up a tech 2 scan tool or equal, oh reminds me EVAP I/M will not complete its drive cycle test, keeps coming up incomplete. Some how I just dont think its related but could be. BCM? PCM? TCM? I would think there would be a DTC or drivability issue accompany it if it was.
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F15actace
September 19, 2009.




Is this a CAN system?

Tiny
Mathiaso
Sep 19, 2009.
Yes I believe it is. Emissions is CALIFORNIA. Does list it as CAN. Here is the vin if it helps
1g8jw54r21y577991

Tiny
F15actace
Sep 19, 2009.
To diagnose a malfunction in the CAN system, a scan tool that can read " U" ( network) is required.
You allready have checkedthe circuit for short, and open, and check the ground and base voltage using a DMM, that is good but
if another module in the nettwork is disconnected and the module that set the DTC begins communicating, the problem is with the other moduleif all wirring connections are good and there is no change after unplugging each of the other modules(ECM, TCM, BCM, ABS) the module in question is likely at fault

Tiny
Mathiaso
Sep 19, 2009.
You saying "and the module that set the DTC begins communicating" in your responce has me wondering if you noted that in my orriginal post I stated there are No DTC's . I have an Actron cp9180 which includes controller area network. please read all my original post to avoid redundant info. Scan tool shows no codes & no pending codes, yet these lights persist ( SRS, ABS, & SERVICE w/wrench)
Here are some samples of yesterdays circut testing and checking


http://www.2carpros.com/forum/automotive_pictures/411145_DSCF0227_1.jpg


Everything has been re assembled

Tiny
F15actace
Sep 20, 2009.
When implying a result of " no change after unplugging.&Quot; are you suggesting I unplug modules and power up the system & or plug & unplug with power hooked up? And which module is in question? The service light (BCM) will come on just because one of the other MIL lights is on. Whats also crazy is the scanner says all mils are off when they are not.

Tiny
F15actace
Sep 20, 2009.
I checked it out, it is not CAN system on yhis car, the can system are on vehicle made from 2003, this one is 2001.
Find out if the vehicle have been wrecked berfore.
This is not only one problem, this is defferent problem.
You will need to work on each system diagram separatly.
I will be searching what harness all of them have in common.
I will let you know as soon I find something. If you do, let me know too.
Talk to you soon.

Tiny
Mathiaso
Sep 20, 2009.
I do in fact have a lot more information, I just needed to get us on the same page & headed in the same direction. I appologize for the mix up about 'CAN'.
Now as for the history of the vehicle- No it most certainly has not been in a wreck. There has been 2 previous owners, ( mother -daughter) It has had a brand new transmission installed & from what I have found out, that seems to be the last major repair it recieved before being dormant for a while.(Carfax)
I understand the requirements for re-calibration of TCM after transaxle replacement and it all seems to have bben done.
Now this is where it gets good.I bought the vehicle with smoke pouring out of the exhaust, barely running, & code 300 (or maybe 303) #3 mis fire detected. In a nut shell, had somehow put too much oil in it and thought the motor was no good. A total of 8.5 qrts to be exact. After an oil change, tune up, and replacement of the rear bank coilpack (front had already been recently done) plus a complete tear down of the intake, plentom, air cleaner hosing, pcv sys, to remove engine oil, the engine has ran outstanding. No codes or SES light. This was well over 600 miles ago.
I am sure you will wonder how well of a job I did or didn't do. I will say this, I do it right or I won't do it at all. When it comes to Diag. I get obsessive.
The SRS module I have sent out to have the software re-installed & reset, with fingers crossed. Its only $49.
Its the BCM that has become the main focus, see if you can find out if it is normal to have mil's lit up without the presence of any DTC's. Even if I don't get to the bottom it, you will be compencated, I am going to go put money on my card now.

Tiny
F15actace
Sep 20, 2009.
You allready donated so , it is o k. I wiill follow you all the way untill we fix it. sorry for writting late because of my 12 hours work a day.
I found something interesting.
let start from the begining:
ABS,SRS, & service(wrench) are on. No DTC's stored or pending.
SRS never been deploy,ABS seem to be performing properly.there is no code for the service light.
here is my point: the problem may be in the BCM .
I'm sending the body system schematic the vehicle, and the data link connector that include the PCM.
let 's cross finger. if the light for the SRS come back after the new SRS intallation,the BCM maybe bad.
bu we must go through all the wirring from and to the BCM. I'm sending the diagram so you can look at it while we are waitting for the SRS. if you need any diagram let me know.


http://www.2carpros.com/forum/automotive_pictures/46384_pic1_2.jpg



save picture as. and zoom to see.
The A/C on the blower that l suddenly cut out for about 5-7 seconds then come back on. 2. speakers in rear doors that does not work are separate issues that we can deal later.

talk to you soon.

Tiny
Mathiaso
Sep 21, 2009.
Yes, yes, & yes. No worries about how long it takes to reply, as long as you keep replying. My friends call me DR. Phil cause I got lots of patience. I am totaly on the same page & have already conducted the wiring harness tests for the BCM. I have aquired all the wiring diagrams for the car but I'm not sure if I have that particular one, I will check at the garage tonight cause the writing isn't readable & gets worse when magnified. In the event that I don't have that diagram, I will be going over the harness again using that one as the referance for distribution. I too, dreadfully suspect the BCM, but want to be absollute before replacing it. Aside from the lights, it seems to perform its functions without any isssue's. Replacing one just because it can't turn the telltales out, its a joke but not funny. Your conclusions so far tell me I have been headed in the right direction. I will add the findings & results of the wiring review tonight.


http://www.2carpros.com/forum/automotive_pictures/411145_BCMnumbers_1.jpg


Tiny
F15actace
Sep 21, 2009.
Wet, wet, wet. I found evidence that the BCM has gotten wet at some point in time.
I was unable to enlarge the diagram without distorting the text, When the image is shrunk the pixels for the writing get screwed up. See if you can send it a little larger because I do want it for referance to continue testing.
It dawned on me today that theoreticly I could check all the leads coming out of the BCM that are supposed have (& correct me if I am wrong) a.5 volt to find a possible confirmation of the problem. What do you think? I believe I have the nessecary diagram to get that done.
Even though the SRS brain is out of the vehicle the light still flashes 7 times. That doesn't make sense to me, does it to you? I thought the flashing was a form of communication from the SRS that it was functional. Now this is obviously from the BCM, does this constitue BCM failure?
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Tiny
F15actace
Sep 22, 2009.

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