Throttle Position Sensor: Adjustments

CLOSED THROTTLE POSITION SWITCH CHECK

The Closed Throttle Position Switch (CTP Switch) is electrically closed (continuity) when the throttle valve is closed (at idle), and electrically open (no continuity) as soon as the throttle is opened.

Throttle Position Sensor V8:

1. Disconnect harness connector from the CTP Switch / Throttle Position Potentiometer (TP Potentiometer), located on the front side of the intake manifold just below the idle air control valve.

NOTE: Terminal numbering on the CTP Switch connector is reversed when compared to the harness connector. Be sure of correct terminal before testing.

^ CTP Switch connector numbering
1 2 3 4 5 6

^ Harness connector numbering
6 5 4 3 2 1

Throttle Valve Switches And Potentiometer Connector Terminal ID:

2. Using suitable multimeter set to resistance range, and throttle valve closed (idle position) check for continuity between CTP Switch terminals 4 and 6.

^ Must be approximately 0 ohms (continuity)

^ IF NOT, CTP Switch adjustment is needed

3. Open throttle valve approximately 10% of travel, check for continuity between CTP Switch terminals 4 and 6.

^ Must be infinite ohms (open)

^ IF NOT or only when throttle is opened more than 10% of travel, CTP Switch adjustment is needed

CLOSED THROTTLE POSITION SWITCH ADJUSTMENT PROCEDURE

NOTE: ^ Throttle body must first be removed before adjusting.
^ Adjusting the CTP Switch also adjusts the TP Potentiometer.

1. With throttle body removed from engine, loosen both screws on the CTP Switch.

Throttle Valve Switches And Potentiometer Connector Terminal ID:

2. Using multimeter set to resistance range, connect multimeter leads to CTP Switch terminals 4 and 6.

Throttle Body V8:

3. Insert a 0.010 in. (0.25 mm) feeler gauge between stop and stop adjustment screw (arrow).
4. Turn CTP Switch fully to the left and then slowly to the right until multimeter displays 0 ohms (continuity).
5. Tighten CTP Switch mounting screws.
6. Remove feeler gauge and insert a 0.012 in. (0.30 mm) feeler gauge between stop and stop adjustment screw (arrow), check multimeter reading.

^ Must be infinite ohms (switch open)

^ IF NOT repeat adjustment procedure

7. If specified resistance values cannot be obtained, replace CTP Switch.