1G Can't Retrieve DTC's from ECU

[-red97rum-]

So here's the deal: I recently picked up a 92 tsi awd and I've been attempting log with mmcd v.1.8 (palm m130) so I can start tuning it, but I can't get connected to the ecu. I get a serial comm error. At first I thought it was my home made cable. I followed the tech article here for making your own passive logging cable. I'm almost sure it's not the cable at fault but rather the ecu not going into diag mode for whatever reason...

I got a cel yesterday and I am not able to retrieve the dtc using a test light between terminal 1 & 12 on the diag port. Good thing is I know it's a coolant temp sensor causing the dtc. But I can't get the thing to blink out the code(s).

So far I've checked all fuses are good except the 60 amp ABS fuse at the battery terminal is gone. Looks like someone chewed it out of there. I'm connecting the test light with the key off and turning the key to on afterwards. The harness does not appear molested in any way.

While searching I've read about ABS causing some issues getting the logger connected. This car does have ABS and the light stays on constantly (hello missing 60a fuse) while driving but I'm not sure if that could be the culprit. Here's a couple pics of my cable I'm using (with a belkin serial hotsync cable), please check it out and let me know if I missed something. I'm going to take the ECU out and check for leaking caps after work. Any ideas why I can't retrieve dtc's?

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[Mindslayer]

I say just buy a cable.

 

[-red97rum-]

And I am all for that if would solve my issue. My concern is that I am not able to retrieve the trouble codes the "old fashioned" way. Is this pointing to a problem with my ECU? A bad fuse? An conflict due to my ABS system not functioning properly? etc.. Has anyone had this problem before? I saw a couple threads with similar but not identical issues and they lead me no where.

 

[TFFC]

I had the same exact problem with the serial com error. It turned out to be my cable! Look at your 9pin connector and make sure you have the wires in the right pin. Those connectors have numbers. I just copied someones off this board, I made mine the exact same, and still didn't work. then I looked at my connector and i had the pins in the wrong hole. Also make sure you have the wire right that has the "tee or Y" for the two connectors right! Also when you just turn key on engine not running, does your check engine light come on? Its quite possible your ecu is dead via the caps leaking. I hope this helps!

 

[-red97rum-]

I'll try that and see what happens. I'm using a serial hot sync cable btw.

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Hey, I have 5 posts now over at dsmap so I'll be requesting a download shortly then I can start really tuning...

 

[steve]

So here's the deal: I recently picked up a 92 tsi awd and I've been attempting log with mmcd v.1.8 (palm m130) so I can start tuning it, but I can't get connected to the ecu. I get a serial comm error. At first I thought it was my home made cable. I followed the tech article here for making your own passive logging cable. I'm almost sure it's not the cable at fault but rather the ecu not going into diag mode for whatever reason...

I got a cel yesterday and I am not able to retrieve the dtc using a test light between terminal 1 & 12 on the diag port. Good thing is I know it's a coolant temp sensor causing the dtc. But I can't get the thing to blink out the code(s).

I'm going to take the ECU out and check for leaking caps after work. Any ideas why I can't retrieve dtc's?

Assuming that the DB9 your using is a male, you have the right pins and the diode is positioned correctly. The diode could be bad and since I can't see the other end of the cable you might not be grounding pin 10 to switch the ECU into datalogging mode.

Test lights can damage the ECU output by drawing too much current. You should try reading the voltage across pin 1 and 12 to see if it's outputting and error code, the on/off heartbeat. It could also be outputting nothing or solid 12v both are an indication of ECU problems.

 

[-red97rum-]

Oh wow, really? Didn't know that, 12v tester is a no no then. I'll borrow my neighbors meter and measure as you suggested.

Indeed I was grounding pin 10 to 12 with the one leg of the cable. Also the diode is facing the right way

DB9:
pin2* ---->---- *Ecu pin 1
pin3* ______|

I have a whole pack of those diodes so I'll try soldering in a new one. I still haven't taken out the ecu yet to check the caps, been busy as hell. Fixed the CEL though, one of the brittle arse wires leading to the temp sensor broke on me. That little sensor made the car run like crap at startup.

 

[steve]

Did you make any progress?

 

[-red97rum-]

Not yet, had a lot of stuff going on this weekend and didn't have a chance to mess with the Talon

Tonight after work I'm going check for the "heartbeat" by measuring between pins 1 and 12. If that works I'll try soldering in a new diode on my logger cable. If that doesn't work I'm going to swap pins 2 & 3 on the cable. If that still doesn't work I'm going to smash my palm with the biggest F-ing hammer I can find

I really need to check the condition of the caps as well. Thanks for the follow up Steve.

 

[steve]

I forgot to ask. Does your computer have a real serial port or are you trying to use a USB to serial adaptor?

 

[-red97rum-]

Actually I'm using a serial hot sync cable for my Palm M130. But yes I do have Laptop with an actual serial port (annoying newer systems don't come with). I think I'll try the laptop with the palm emulation software while I'm at it..

 

[steve]

dont switch pins 2 and 3 if your going to try it on the pc. (pins are reversed between palm and pc for sync)

I'd put money on the rx/tx pins being in the wrong setup for your cabling.

Pins 2 and 3 are the RX and TX pins?

If his serial hotsync cable works between his PC and Palm then his logger cable nees to terminate in a male DB9 and looking at the backside of the connector pin 1 is on the right just like in the pictures above.

So I don't follow what your trying to get at?

 

[-red97rum-]

I got it working. I ended up making a completely new cable and viola! Been tuning the last couple nights and I got her feeling pretty good at 16-17 psi of boost on pump with the EVO 16g. Thanks for the help.