E026

Diagnostic Chart.:

ISC Circuit:

DESCRIPTION:

The throttle switch is part of the ISC motor assembly. The PCM/ECM provides a 5.0 volt signal on CKT 427. When the throttle lever contacts the ISC plunger, the throttle switch closes. When the throttle switch is closed the input voltage is low. Code E026 sets when the PCM/ECM detects a TPS signal greater than 20° (accelerator being applied), but the throttle switch remains closed.

TEST CONDITIONS:

1. Code E021 and E022 clear.
2. TPS between 20 and 75 degrees.

FAILURE CONDITION:

Throttle switch input to PCM/ECM closed for 1.8 seconds.

ACTION TAKEN:

1. PCM/ECM turns on "SERVICE ENGINE SOON" light.
2. PCM/ECM assumes open throttle when brake is off or TPS is more than 18°.
3. PCM/ECM assumes closed throttle if brake is applied and TPS is 18° or less.

NOTES ON FAULT TREE:

1. A binding or sticking TPS can cause this code to set.

NOTE ON INTERMITTENTS:

Select PCM/ECM input EI72. Manipulate affected wiring and connectors and observe display. If the throttle switch state changes momentarily, "Lo X" will appear on the display.