OBD2 Scanner Can't Read 02 Yukon while "Service Engine Soon" MIL Light is lit


Yukon02
05-20-2007, 09:45 PM
I have a 2002 GMC Yukon Denali that I have only had for a few weeks. Last week the “Service Engine Soon” MIL light came on. I took it to AutoZone to have them read the code (they do that for free here). The guy was unable to read anything from the computer. I wasn’t convinced so I took it to another AutoZone. This guy got the same result but said something to the effect of “Oh, I can’t read ‘Service Engine Soon’ lights, only ‘Check Engine’ lights. Take it to a service station and they can read that code.” So I immediately took it to the service station across the way. I watched them as they tried to scan with a similar looking tool, and eventually just pulled the battery cable and put it back. They said that it was on because the gas cap wasn’t tight enough (seemed plenty tight!). It wasn’t more than a day later when the light came on again!

I decided to go to Checker and get my own scan tool! I purchased the Innova 3130 ($200 scan tool @ http://www.canobd2.com/ (http://www.canobd2.com/)). I tried it on several cars and after mastering the technique I tried it on my Yukon. Nothing! When I plug the tool in it the tool powers up but I don’t get any signal, I press the scan button (which is also the power button, what genius designed that?) the tool simply turns off! It’s like it’s not even connected.

The wires in the back look fine and the connector is pushed all of the way in and is solid! I checked all of my fuses and they are all fine. I am not sure what to try next! I suppose I could activate OnStar and get the code from them but I would really like to figure this out!

Thanks!
Nathan

veedubmechanic
05-22-2007, 10:07 PM
u sure the batteries in the scan tool arent dead?

maxwedge
05-23-2007, 09:30 AM
Welcome to AF. Or the body/feed liter fuse is bad. Check all the wires in the link plug and make sure no breaks or the pins are spread.

Yukon02
05-23-2007, 12:04 PM
u sure the batteries in the scan tool arent dead?

Over 6 scan tools have attempted to scan this vehicle, none with any success! Every one of them had the ability to read other vehicles. I have also pulled and checked every fuse I could think of but will focus on the one listed in the last post and report back.

--Nathan Zaugg

2000CAYukon
05-23-2007, 08:19 PM
Check pin 5 for ground and 16 for battery voltage. See http://www.auterraweb.com/obdiipinout.html

//2000CAYukon

Yukon02
05-25-2007, 12:45 AM
Check pin 5 for ground and 16 for battery voltage. See http://www.auterraweb.com/obdiipinout.html

//2000CAYukon

Pin 5 was grounded, pin 16, however had no voltage. I took a closer look at some of the fuses test light and found that the fuse labeled "CIGAR" was blown in such a way that it was hard to see. I replaced it and was able to read the codes. Now I have to figure out what those mean:

CODE #1: P1518 - PCM to TAC Module Serial Data Circut
CODE #2: P0440 Evaporative Emission System
CODE #3: P0440 (Pending) Evaporative Emission System

FREEZE FRAME DATA FOR P1518:
Fuel Sys 1 OL
Fuel Sys 2 OL
Calc Load (%) 0
ETC (°F) 190
STFT B1 (%) 0
LTFT B1 (%) 0
STFT B2 (%) 0
LTFT B2 (%) 0
MAP (in HG) 25.1
Eng RPM 0
Veh Speed 0
MAF (lb/min) 0
TPS (%) 15.2


And yes, I have checked my gas cap! I'll be extra sure to make sure its on as tight as I can get it just to be sure. I have cleared the codes and will watch for the light again.

Any ideas about the P1518 code?


Thanks!
Nathan

maxwedge
05-25-2007, 03:20 PM
I thought after I told you cigar liter fuse, that all was ok? Go to troublecodes.com for code info.

Yukon02
05-25-2007, 03:26 PM
I thought after I told you cigar liter fuse, that all was ok? Go to troublecodes.com for code info.

Sorry, I did only a visual inspection of the fuse. The crack in the fuse was not visible. http://www.troublecodes.com doesn't appear to be a valid site.

Thanks!
Nathan Zaugg

2000CAYukon
05-25-2007, 04:58 PM
www.troublecodes.net/GM but that is mostly for OBD 1 codes.

Looking at my 2000 Factory manuals, this code can be set:
- when that battery voltage is low
- short to B+ on the TAC module
- TAC module ignition feed is shorted to a B+ supply circuit
- TAC module is bad

I would see if it comes back.

//2000CAYukon

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