Cruise Control Drops Out Intermittently and/or May Not Set After Drop Out

The cruise control drops out intermittently and then may not respond to SET command after drop out occurs. PCM/EC diagnostic trouble codes (DTCs) P1640 or P1641 may be stored in PCM memory.

The cruise control system controlled by a quad driver module (QDM) located within the powertrain control module (PCM). The quad driver module controls the following functions:

If a fault occurs in any of the above circuits, the PCM will set and store DTC P1640 or P1641, command the Service (Wrench) telltale On, and disengage the cruise control clutch.

To properly diagnose this condition, make sure to follow the procedures in the appropriate year "Powertrain Controls Service Manual" for DTC P1640/P1641. If the QDM test indicates a fault with the "Service" (Wrench) telltale bulb or instrument panel cluster housing, refer to the following procedure to properly inspect and repair the condition.

1. Remove the instrument panel cluster from the instrument panel. (Refer to "Instrument Panel Cluster" removal procedure in the appropriate year "Audio System & I/P Cluster Service Manual.")
2. Inspect the Service (Wrench) Telltale bulb to make sure it is not burned out and it is securely held in place by the instrument panel cluster housing.

•	Remove the bulb and verify Service (wrench) bulb is not burned out, by checking continuity of Service (wrench) bulb filament is open (bulb burned out).

•	Inspect the four points in the socket on the instrument panel cluster housing shown in illustration. If any of these points are bent or broke, the bulb will not be retained securely by the instrument panel cluster housing, and the instrument panel cluster housing must be replaced.

Important: There can be minor variations in instrument panel cluster housing.

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After replacing instrument cluster housing, verify that condition has been repaired by performing the bulb check (turn ignition key to "RUN," and verify Service (wrench) bulb turns On for 1-2 seconds and then turns Off), and brief test drive to ensure cruise control operation. If condition still exists, refer to the appropriate year "Powertrain Controls Service Manual" to diagnose condition.

•	If the four points shown in the illustration are not bent or broken, insert the bulb into the instrument panel cluster housing socket. When turning the bulb, you will be able to feel it click in place. The bulb must also be snug in the socket.

3. If there is no damage to the instrument panel cluster housing socket and the bulb fits snug in the socket, refer to the appropriate year "Powertrain Controls Service Manual" to diagnose DTCs P1640 and P1641.

To receive credit for this repair during the warranty coverage period, submit a claim through the Saturn Dealer System for N4170 (Replace Cluster Housing Assembly) or N0647 (Replace Cluster Telltale Bulb), or if another procedure is performed, refer to the appropriate Electronic Labor Time Guide for the correct Labor Operation Code and Time.