Cruise Control - Surging Above 45 MPH

Bulletin No. T 85-42
File In Group 9
Number 25
Date Jan. '85
SUBJECT: CRUISE CONTROL SURGING CONDITION AT HIGHWAY SPEEDS

MODELS AFFECTED: 1983-1985 ELDORADO AND SEVILLE


Some vehicles may experience a slight surging condition above 45 MPH with cruise control engaged. This condition may be accompanied by a slight accelerator pedal movement. However, the condition may not result in speedometer fluctuation either with or without digital speedometer head. If this slight surge condition is experienced, the following procedure should be followed:

1. Verify that surging condition exists only while cruise control is engaged.

2. Check the vacuum system for disconnected or leaking hoses.

3. Temporarily secure the speedometer cable to the brake booster and servo mounting bracket with a tie wrap to eliminate cable whip.

4. Test drive vehicle. If the condition is reduced, replace the speedometer cable and case.

NOTE: Before installing replacement speedometer cable, lube the replacement cable and check that it turns freely in the case.