CODE E031, PARK/NEUTRAL SWITCH CIRCUIT Oldsmobile Toronado IV

CODE E031, PARK/NEUTRAL SWITCH CIRCUIT

The Park/Neutral (P/N) switch contacts are part of the neutral start switch and are closed to ground in Park or Neutral, and open in Drive. The ECM supplies ignition voltage through a current limiting resistor to circuit No. 434 and senses a closed switch when the voltage on circuit No. 434 drops to less than one volt. The ECM uses the P/N signal as one of the inputs to idle air control, EGR and VSS diagnostics.

Code 31 will set under the following conditions

1. If circuit No. 434 indicates P/N (grounded) while in Drive range and 4th gear TCC engaged, EGR would be inoperative, resulting in possible detonation.
2. If circuit No. 434 indicates Drive (open) at start up, a drop in idle may exist when gear selector is moved into Drive range.
3. If transaxle 4th gear switch has an intermittent open, ECM thinks vehicle is in 4th gear and will set Code E031. NOTE: Test numbers refer to test numbers on diagnostic chart.

1. Checks for a closed switch to ground in "PARK" position. Different types of "Scan" testers will read P/N differently. Refer to Scan" tester operators manual for type of display used for specific tester.
2. Checks for an open switch in drive range.
3. Ensure that on-board diagnostics EI74 indicates drive HI"), even while wiggling shifter. This will test for an intermittent or misadjusted switch in drive or overdrive range.

Code E031, Park/Neutral Switch Circuit. Scheme 151