jeeper26

I need help with my "communication" issue folks. I have successfully tested the pins according to post #6 http://www.cherokeetalk.com/forum/f2...ot-read-16508/ I have checked all fuses and they are good I have inspected and taken the odb2 connector apart and cleaned it. I am using an AutoEnginuity scan tool on my laptop. When I connect the scanner it will recognize it but will not connect. It will on occasion communicate successfully with the jeep and give me a no diagnostics code found then immediately disconnect and try and connect again with no success. Does anyone have any suggestions on what to check next? below is a screen shot of what is happening, I connected and it drop and displayed the error box in the bottom right portion of the picture.

jeeper26

rechecked and reterminated my grounds for good measure and I still cannot get the scanner to communicate. HELP

jeeper26

Bump

southsidecatac

So, the issue is either with your laptop computer or the OBDII on your vehicle. Put a handheld tool on the jeep to see if you can get proper readings. If so, then you need to call tech support and figure out why your scan program is not working.

jeeper26

sorry I forgot to mention that I have tested my scanner on other vehicles and it works fine. Also that the smog station cannot communicate with the jeep either. I just rebuilt the motor on this thing and repaired a few misc items and it is in great working order and runs perfect now....I just cant prove it to the state to get my tags

CCKen

Refer to post #12 above.

Note the SCI Receive and SCI Transmit pin cavities in the DLC. Verify these pin cavities are not corroded and not enlarged by someone shoving meter probes in them.

A scan tool will not communicate with defective DLC SCI pin cavities.

jeeper26

assuming the cavities are good (cleaned and corrosion free) what would be the next step?

CCKen

I would check for high resistance in the PCI wires from the DLC to the PCM and TCM.

From DLC pin cav 6 (Light Green/Black tracer wire) to pin cav C29 in PCM Connector C3. From DLC pin cav 7 (Pink wire) to pin cav C27 in PCM Connector C3.

And From DLC pin cav 7 (Pink wire) to pin cav 14 in TCM Connector.

If you have Anti-Lock Brakes the ALB Controller is also in the SCI Transmit circuit.

If you need pin-outs of these connectors let me know. I'll have to fire up my photobucket to access them.

Photontraveler

When I had this problem my virus software, Windows Defender, was causing my laptop not to connect. I uninstalled it, used my OBDII software then reinstalled windows defender.................I hope this helps.

jeeper26

Thanks for walking me through this Ken, I printed out a couple of test procedures you outlined in several other post and diagrams. I will see what i find tonight and hopefully have found where the problem is. One more thing, i have an intermittent airbag light while its running is this related?

CCKen

Don't know if the AB light means anything related to your problem actually. AB light on has been attributed to a bad AB Control Module, or Clockspring commonly. Do ou have any other symptoms?

Did you test the CCD Bus (+) and (-) voltages? The procedure should be in that bunch of posts I made.

jeeper26

only thing I have going with the AB ight is it flashes on and off sometimes no other symptoms. Yes tested CCD bus voltages and i get 2.49 and 2.5

jeeper26

Just tested, pin 6 to PCM = 0 ohms, pin7 to PCM =0 ohms, pin 7 to TCM = 15ohms

CCKen

Do you have Anti-Lock Brakes?

There's a splice (S139) in that Pink wire that goes from DLC #7 to the PCM and TCM that includes the ALB Controller. If you do have ALB, unplug the Controller and see what what happens. If you do not have ALB the splice is in the large wiring harness that goes along the firewall and is located around the Duty Cycle EVAP Solenoid. Wiggle the harness in this area to see if the resistance changes.

15 Ohms is a little too high. The max should be no more than 5 Ohms.

Based on your good CCD Bus voltages, I don't think your CCD Bus or the modules are bad, just the SCI Transmit circuit to the TCM (ALB?).

Edit: See if your scanner will connect/communicate with the TCM disconnected.

jeeper26

Update: no ABS, tried to connect with the TCM disconnected and still no luck. Wiggled harness and rechecked I get from DLC pin7 to TCM pin 14= 0.08 ohms. It did link up once and then upon successful communication with the jeep it immediately disconnects and tries to sync up again. Am I going to need to throw in the towel and get a new PCM? I just wish one of these tests would fail so I know for sure what the problem is.