Engine Running Test Mode

Connect diagnostic readout box to engine harness connector. Ensure read/hold switch is in "READ" position. Start engine and observe readout box display. When the O2 sensor is at operating temperature, the display will show you if the system is switching rich-lean by alternately displaying "0" and "1" when in closed loop ("0" - Lean, "1" - Rich).
When the engine is running in Neutral or Park and the O2 system switching is displayed, the idle motor system can be checked by moving the read/hold switch to the "HOLD" position. Engine speed should increase to about 1500 RPM. With the engine speed more than 1500 RPM, an "8" will be displayed next to the "0" or "1" when the detonation sensor is operating.
When the engine is running, O2 switching is displayed and the read/hold switch is in "READ" position, depress and hold the ATM button until the desired engine running test code is displayed. Release ATM button. Move read/hold switch to the "HOLD" position. The logic module will display the selected sensor output or will operate the engine in a specific mode for system diagnosis.
Battery voltage, manifold vacuum and vehicle speed are actual readings and no correction is required. Coolant sensor and engine RPM readings are to be multiplied by 10 for actual readings. All other readings are to be divided by 10 for actual reading.

NOTE: If using a diagnostic readout box other than Chrysler Diagnostic Readout Box (C-4805), follow manufacturer's instructions on how to connect readout box and obtain codes. Some of these other readout boxes will display information that is not contained in this testing. This information may not be relative to diagnosing a problem. Only information in this article should be used during diagnosis.