Oil Pressure Sensor: Service and Repair

Typical Throttle Body Assembly:

Throttle Body Removal:

Throttle Body Identification:

The throttle body assembly repair procedures cover component replacement with the unit on the vehicle. However, throttle body replacement requires that the complete unit be removed from the engine. An eight digit part identification number is stamped on the bottom of the throttle body casting next to the coolant cover. Refer to this number if servicing, or part replacement is required. For identification of parts during repair, refer to the disassembled view.

Clean The throttle bore and valve deposits may be cleaned on-vehicle, using carburetor cleaner and a parts cleaning brush. Follow instructions on container. DO NOT use a cleaner that contains methyl ethyl ketone, an extremely strong solvent, and not necessary for this type of deposit.

The throttle body metal parts may be clean following disassembly, in a cold immersion-type cleaner such as GM X-55 or equivalent.

NOTE: The TPS and IAC valve should not come in contact with solvent or cleaner, as the may be damaged.

REMOVE OR DISCONNECT:

1. Negative battery terminal.
2. Partially drain radiator, to allow coolant hoses a throttle body to be removed.
3. Air inlet duct.
4. IAC valve and TPS electrical connectors.
5. Vacuum harness connector.
6. Coolant hoses at throttle body.
7. Throttle, TV (transmission control), and cruise control cables.
8. Throttle body retaining bolts.
9. Throttle body assembly.
10. Flange gasket and discard.

NOTE: Use care in cleaning old gasket material from machined aluminum surfaces. Sharp tools may damage sealing surfaces. Clean gasket surface on intake manifold.

INSTALL OR CONNECT:
1. New flange gasket.
2. Throttle body assembly.
3. Throttle body retaining bolts. Tighten Throttle body attaching bolts to 25.0 N-m (18 lb. ft.).
4. Throttle, TV (transmission control) and cruise control cables.

IMPORTANT: Make sure throttle and cruise control linkage does not hold throttle open.

5. Coolant hoses to throttle body.
6. Vacuum harness connector.
7. IAC valve and TPS electrical connectors.
8. Air inlet duct.
9. Refill radiator to replace lost coolant.
10. Negative battery terminal. With the engine "OFF," check to see that the accelerator pedal is free: Depress pedal to the floor and release.
11. Perform the "Idle Learn Procedure." The PCM will need to relearn the IAC valve pintle position following battery reconnect.

REMOVE OR DISCONNECT:
Throttle body from intake plenum. Inspect Replacement throttle body for items to be transferred from old unit.

DISASSEMBLE:
Throttle body removed from engine, following component repair procedures.

ASSEMBLE:
Replacement throttle body with transferred parts, following component repair procedures.

INSTALL OR CONNECT:

1. Replacement throttle body to intake plenum.

NOTE: The minimum throttle valve position is critical to vehicle performance and component durability. If the throttle valve is adjusted too far open, it will cause the IAC valve pintle to constantly bottom on its seat and result in early valve failure. If the throttle valve is not open far enough, the vehicle may not start in cold weather or may stall during warm-up.

IMPORTANT: Adjustment should be performed only when installing a replacement throttle body. The idle stop screw is used to regulate the minimum throttle valve position. On original equipment throttle bodies, it is adjusted at the factory, then covered with a plug to discourage unnecessary readjustment.

2. Adjust minimum throttle valve position.

ADJUST:

Adjust Tool required: Tech 1 "Scan" Tool

1. Back throttle stop screw out until an air gap between the screw and the throttle lever can be seen by looking downward from above the throttle body.
2. Turn the stop screw in until it just contacts the throttle lever.
3. Turn the stop screw in 1 1/2 turns further.
4. Refer to "Idle Learn Procedure." The PCM will need to relearn the IAC valve pintle position following battery reconnect.
5. Connect Tech 1 "Scan" tool to ALDL connector.
6. Place transmission selector in "PARK."
7. Start engine, allow it to reach normal operating temperature (about 90°C/194°F) and "Closed Loop."
8. Observe Idle Air Control (IAC) valve counts displayed on Tech 1 "Scan" Tool.

IMPORTANT: Battery must have been disconnected during replacement procedure and then reconnected before checking IAC valve counts. This will enable the PCM to relearn the IAC valve pintle position. IAC valve counts should be checked with all accessories "OFF" (A/C, rear defog, etc.), transmission in "PARK," and engine cooling fan "OFF." Make sure throttle and cruise control cables DO NOT hold throttle open. With engine stabilized, IAC valve position should be 10 to 20 counts. If not, repeat adjustment procedure.