E027

Code E27:

ISC Circuit:

DESCRIPTION:

The throttle switch is part of the ISC motor assembly. The ECM provides a 5 volt reference on CKT 427. When the throttle lever contacts the ISC plunger, the throttle switch closes. When the throttle switch is closed, throttle switch input voltage is low. Code E27 is designed to detect a throttle switch that is always open.

TEST CONDITIONS:

Continuous monitoring.

FAILURE CONDITIONS:

1. Throttle switch was never closed during the last key cycle, in which the engine was running and the brake was depressed.
2. Throttle switch has not closed in the current key cycle.

ACTION TAKEN:

1. ECM turns "on" SERVICE ENGINE SOON" telltale.
2. ECM assumes throttle switch is closed if brake is applied and TPS is 18° or less.
3. ECM assumes throttle switch is open if brake is not applied and TPS is greater than 18°.

NOTES ON FAULT TREE:

1. If the ECM does not detect that the throttle switch has opened or closed, the Fuel Data Center will display E.7.2.

2. When the ECM detects the switch open and closed the Fuel Data Center will alternately display E.7.2 and E.0.0.

NOTE ON INTERMITTENTS:

Check ISC plunger mechanical operation. Check throttle body for coking, throttle spring, cruise and TV cable for binding.