Hi all im having an issue with the ecu not communicating with the scan tool i have checked the fuses all are good my overhead computer isn't working as well just shows "c" and no other data (not even direction or temp) i have checked for power on pin 16 and it is there scan tool powers up ... just cant communicate i replaced the ecu about a year ago and everything was working then, the engine runs great .... save for low gas mileage...

i am also having issues with the ABS and brake lights on all the time even with truck sittting still no flicker/blinking i was thinking of replacing the speed sensors and hubs but just needed some more info the abs is the older one (not the kelsey-heyes unit) please any help on either of these issues would be great THANKS!!

 

Use a digital voltmeter to check the DLC connector:
1. Check ground continuity. Connect the positive (+) meter lead to DLC pin 4. Connect the negative (-) meter lead to the negative battery terminal. Use jumper wires as needed. Do not connect to a body or chassis ground; go directly to the battery terminal if at all possible. With the ignition on, voltage drop across the ground terminal should be 0.1 V or less. Repeat for DLC pin 5. An open circuit or high ground resistance prevents the ECM from entering diagnostic mode.

2. Check voltage on pin 2 of the DLC. The PCM transmits data on this pin. Connect the positive voltmeter lead to the class 2 serial data pin and the negative lead to either pin 4,pin 5, or a known good ground. With the ignition on, voltage on the class 2 serial data pin should be either 5 V or fluctuating between 3.5 and 5.0 V. If the circuit is open, the ECM cannot transmit data to the scan tool.

Search the site on how to check the ABS wheel speed sensors with a multimeter.

 

thanks i will do this as soon as it warms up abit outside..18 degrees outside right now :P

 

OK so decided to brave the cold 1: battery negative to pin 4 .119 battery negative to pin 5 .164 2: pin 2 to 4 or 5 nothing what now?

 

Cigarette lighter work?

 

Yes cb is plugged into it and the scanner turns on (powered buy OBD plug)

 

does anyone else have any ideas on what to check next on my issue? any help is appreciated