skiiirt Posted August 1, 2004 Report Share Posted August 1, 2004 So here I am driving to work, the car started fine but I noticed something wasnt quite right. the idle was a lil jumpy, fluctuating maybe 100 - 300 rpms. About 2 blocks away I get the SES light. No problems, added a little 5w just in case. Now I have read through the manual scan process for the SES light. I don't understand a freakin word of how to decode the damn thing. Anyone want to give error code diagnosing for dummies. I watched the demo and I don't get it. 12,12,12,25,25,25,12,12,12 how you get that out of a blinking light is beyond me. Can someone maybe elaborate on this, I dont want to give the stealership my $60 to scan my car. In Canada we dont have those fancy automotive stores that will do stuff for free. Any assistance would be appreciated Quote Link to comment Share on other sites More sharing options...
THe_DeTAiL3R Posted August 1, 2004 Report Share Posted August 1, 2004 What year is your car? If it is 88-94(?) and is OBD1 than you can check the codes. a code 12 mean everything is good. It is one blink followed by 2 short blinks (1+2=12) I forget where the procedure is, but its very easy Quote Link to comment Share on other sites More sharing options...
skiiirt Posted August 1, 2004 Author Report Share Posted August 1, 2004 hmmm if i were to record this with a video camera could someone decode my ses light? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted August 1, 2004 Report Share Posted August 1, 2004 so you pulled codes 12, and 25 from your car? 12 means the computer is working or that "hey, i'm a PCM, i'm here!!" but 25 means : MANIFOLD AIR TEMP (MAT) or INTAKE AIR TEMP (IAT) CIRCUIT (HIGH TEMP) ok but in any case i'm asumeing that you know the paperclip trick to get the computer to go into diag mode. then the light will flash once pause flash twice it will do that 3 times, thats code 12, then it will flash any additional codes like 2 times then 5 times for code 25 and so on and so fourth, when its done displaying codes it will go back to code 12 Quote Link to comment Share on other sites More sharing options...
god910 Posted August 1, 2004 Report Share Posted August 1, 2004 hmmm if i were to record this with a video camera could someone decode my ses light? Yes. It's very easy. As was stated before. There will be a short pause inbetween flashes for a code, and long flashes in between codes. Quote Link to comment Share on other sites More sharing options...
skiiirt Posted August 1, 2004 Author Report Share Posted August 1, 2004 ok basically it went flash pause flash flash flash pause flash flash flash pause flash flash flash flash flash flash pause flash flash pause flash pause flash flash Assuming that this means its a error 42? Quote Link to comment Share on other sites More sharing options...
THe_DeTAiL3R Posted August 1, 2004 Report Share Posted August 1, 2004 ok basically it went flash pause flash flash flash pause flash flash flash pause flash flash flash flash flash flash pause flash flash pause flash pause flash flash Assuming that this means its a error 42? flash pause flash flash = code 12.. (normal) flash flash flash flash pause? Is that maybe a 40? if it was flash flash flash flash pause flash flash that would be 42 hmmm if i were to record this with a video camera could someone decode my ses light? Maybe you should do that... Quote Link to comment Share on other sites More sharing options...
skiiirt Posted August 1, 2004 Author Report Share Posted August 1, 2004 haha somehow i knew it.. but i think im correct with the 42. it I think this is what it's doing. I couyld be wrong. I'll videotape it tonight. goin cruisin now 12,12,12,42,12,12,12 Quote Link to comment Share on other sites More sharing options...
DiscoStudd Posted August 1, 2004 Report Share Posted August 1, 2004 I found a website a few years ago that listed just about all cars with OBD 1 and what their DTC's meant. The site is gone now, but fortunately I saved the ZIP file. Here's the file: http://www.users.qwest.net/~ace69/DTClist.zip Unzip the file and you'll find HTML documents. Click on the folder for GM and find your year and motor listed and click on that... BTW, that code 42 should have flashed 3 times before going back to code 12. Code 12 will flash 3 times at the start and 3 times after all the codes have been displayed. If all you get is a continuous code 12, then there are no codes stored... Quote Link to comment Share on other sites More sharing options...
skiiirt Posted August 2, 2004 Author Report Share Posted August 2, 2004 Must have been me not paying attention. I did it again this afternoon and confirmed the 42 12,12,12,42,42,42,12,12,12 Thanks everyone who helped out Quote Link to comment Share on other sites More sharing options...
White93z34 Posted August 2, 2004 Report Share Posted August 2, 2004 Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system. During cranking, the timing is controlled by the ignition module and the ECM grounds the EST line. It expects to see no activity on this line at this time. When the ECM enters EST mode, it applies +5 volts to the BYPASS line and expects to see voltage variations on the EST line. Reasons for the ECM to set Code 42: * System in BYPASS mode (i.e. EST line supposedly grounded) but activity sensed on EST line * System in EST mode (i.e. BYPASS line driven with +5 volts) but no activity seen on the EST line Possible causes include: 1. BYPASS line is open or grounded 2. EST line is open or grounded 3. Poor connections between ignition module and ECM 4. Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise 5. Faulty or incorrect ignition module 6. Faulty ECM Quote Link to comment Share on other sites More sharing options...
Dan94Z34 Posted August 3, 2004 Report Share Posted August 3, 2004 go here http://www.troublecodes.net/GM/ Quote Link to comment Share on other sites More sharing options...
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