1999 Toyota Camry CE 2.2L no mil lamp no communication

Car Question:

Working on my 1999 Camry, I got no scanner communication problem. I tried my scanner with another car and it worked. I am assuming a wiring short problem whenever there is no communication on the scanner. Where do I go from here?

ATS Adviser:

When we say wiring problem during no communication means two different things: a breakdown in the wiring circuits (shorted, open, cut) or faulty module/s (will cause bus network to shutdown).

Quick way to test these is to use your voltmeter. At key on engine off (KOEO), probe pin 7 of the DLC pin terminals with the ground pin 4 or 5 as your ground, you should get 12 volts. If not, disconnect the engine control module and the air bag module. Do it one at a time. If the communication is restored, that module or its wirings are shorted. You can check the short by checking the power and ground supplies.

In case the suspect is the ECM module, check the voltage reference at tps, vapor pressure and map sensors. It has yellow color wires and should read 5 volts at KOEO. If not available, unplug each sensor one at a time and see if communication is restored. If it does, verify by checking the ground supply wires shown as brown color. None should read higher than 0.250 volt at KOEO. If OK, replace the affected sensor.

Check this approximate wiring diagram below for this problem. When testing the DLC, measure voltage at pin 7 for bus voltages called "SIL". Notice also the power supply at pin 16 and grounds at pin 4 and 5 (including E1) shown in brown color.

1999 Toyota Camry 2.2L Bus Wires

For more details, you can get an exact wiring diagram from most parts stores when you buy the parts or join ATS.

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