2000 Dodge Dakota 4.7L no communication mil lamp on

Truck Question:

Not sure what to do but my scanner won't communicate with this 2000 Dakota after I plugged it on the DLC terminal. I checked DLC terminal pins 4 and 5 for ground and pin 16 for power at key on engine off (KOEO) and all of them read normal. I can see voltage readings on pins 3, 6, 7, 11 and 14 but I am at a lost on how to read them.

ATS Adviser:

Here is the breakdown of the DLC pin terminals:

pin 3 is the CCD (+) bus wire
pin 4 and 5 are both ground supplies
pin 6 is SCI receive bus wire
pin 7 is SCI transmit bus wire
pin 11 is CCD (-) bus wire
pin 14 is SCI receive bus wire
pin 16 is the power (battery) voltage supply

To troubleshoot bus wire network, get hold of the computer data bus diagram or you can browse the ATS 2003 Dodge diagram for bus communication topic under wiring diagram link.

When testing the bus wires, CCD bus wires (pin 3 and 11) when probed with pin 5 must have 2.5 volts each at KOEO. Whereas SCI bus wires are only used by the scanner for internal communication to the vehicle computer or PCM. SCI is needed to check for testing the PCM and transmission modules only. To check if SCI bus wires are OK, disconnect the scanner and you must get 12 volts + pin 5 at KOEO.

If you don't get 2.5 volts at the CCD bus wires, check voltages at bus junction box # 3 and check pin terminal connectors going to the following CCD modules: central timer, radio, instrument cluster, air bag, ABS, overhead console. You can also monitor pin 3/11 with battery disconnected and expect to get 60 ohms there. If not, disconnect the CCD modules one at a time until ohmmeter reading returns to normal.

Check this approximate wiring diagram below for this problem. When testing the DLC, measure voltage between pin 11 {CCD(-)} and pin 3 {CCD(+)} for bus voltages.

2000 Dodge Dakota Bus Wires

You can get an exact wiring diagram from most parts stores if you ask for it when you buy the parts or join ATS.

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