E050

Diagnostic Chart.:

PCM Wiring:

DESCRIPTION:

The second gear pressure switch is a normally closed switch located within the transmission. This switch is opened by second gear oil when the line pressure is high enough to allow shifts without clutch slippage. EI79 displays the voltage status of the second gear pressure switch input (PCM terminal C10). When the switch is closed the input will be LO and will switch HI when the vehicle is in second, third or fourth gear with sufficient line pressure to allow 3-2 downshifts.

Transmission line pressure is regulated by the vacuum modulator in response to intake manifold vacuum. At high engine load (low vacuum) the line pressure is high, and at low load the pressure is low. The PCM calculates engine vacuum by subtracting MAP from BARO. If under the given vacuum conditions EI79 is not correct, the code will set.

TEST CONDITIONS:

1. Codes E031, E032, and E034 not set.
2. Gear status from the BCM indicates D4.
3. PCM is commanding third or fourth gear.
4. BARO greater than or equal to 82 kPa.

FAILURE CONDITIONS:

1. Vacuum less than or equal to 4 kPa (12" Hg.) and second gear pressure switch is closed (EI79 status LO) for 15 seconds.
2. Vacuum greater than or equal to 40 kPa (12" Hg.) and second gear pressure switch is open (EI79 status HI) for 15 seconds. (The PCM calculates engine vacuum by subtracting MAP from BARO.

ACTION TAKEN:

1. Code set, no service lamps or messages displayed.

NOTES ON FAULT TREE:

1. The PCM input test EI79 will test the second gear pressure switch and circuit.

2. When PCM snapshot is selected the snapshot on the code set feature will identify the recorded code snapshot. If E050 caused the recording of the snapshot it can be used to isolate possible causes.