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Intermittent Cruise Control
Hi! I've "lurked" for a while and I have searched all that I can find elsewhere
before this, my first post. My red '99 (welded - FPS) was t-boned by a red-light
runner and totaled last month at 78k. I have just replaced it with a black '99
with 49k (does anybody recognize a black '99 Texas car, last 4 on the VIN is
1773, as a cam weld before I pull the covers?). The dead one and the black one
both exhibit the same problem:
After switching the cruise control ON, pressing SET/ACCEL (at any valid speed)
usually results in a brief flash of the CRUISE light and no engagement - though
occasionally it will engage and perform faultlessly! Does anyone have a sequence
of tests I can use to determine the root cause of the problem? I have checked
for standard OBD-II codes and there are none.
BTW, in anticipation of being flamed for audaciously acknowledging that I use
cruise control in my SHO, I find it to be the easiest way to avoid speeding
tickets after closing my pub in the early hours of the morning - without the
cruise control there is just too much temptation to clog on...!
I use the cruise all the time when by myself. Hard to use it with list members.
The system is electronic and has a lengthy IIRC diagnostic tree.
I worked on a 1995 ford Aerostar just before I left the shop floor that had the
same problem, that truck was the cruise module down by in the foot well.
Paul can post the Diag by system chart if there is one.
Just a guess, but what if the brake switch was stuck on? Do your
brake lights reliably function normally? I have had the brakes get
stuck on, and had the switch on the brake pedal once that they
wouldn't work at all. That is what disengages the cruise.
Next time it does this, hit resume and see if it does it again (or by
luck it may engage and remain that way)... Reason I say that is
because if the cruise module (electronics) gets turned off resume
won't do anything as the system would need to be turned on and set,
however if the electronics remain "alive" and the brake signal is what
tripped it back off then you would see it try to engage again when you
There is probably a more formal procedure but I am trying to eliminate
the brake switch input to the cruise module. If it does seem to
possibly be the brake switch, the next question is if the
Multi-Function Switch is in the loop with that input to the cruise
control in the GEM or not.
Hope that helps,
Scott "I love my cruise even at 100" Krietemeyer
Inspection and Verification
(Start Testing Here)
Verify the customer's concern by operating speed
control system to duplicate the condition.
Inspect to determine if one of the following
mechanical or electrical concerns apply:
VISUAL INSPECTION CHART
Mechanical Inspect and verify that:
Actuator cable is adjusted properly without
holding the throttle open or increasing idle speed.
Throttle linkage operates freely and smoothly
when connected to the actuator cable and
speed control servo.
Verify proper horn operation
Verify stoplamp operation
check circuit fuses: Fuse Junction Panel
Fuse 28 (15A)
Fuse 6 (15A)
Speed Control Indicator Bulb
Inspect and verify that:
Connections are complete with no loose wires or
Wiring is not broken, shorted or corroded.
Wiring is not misrouted.
If inspection reveals obvious concern(s) that
can be readily identified, repair as required.
Perform the Self-Test Diagnostics.
See: Extracting and Clearing Codes (Self-Test Diagnostics)
Extracting and Clearing Codes
WARNING: THIS TEST IS A KEY ON
ENGINE OFF (KOEO) TEST ONLY THAT IS CONDUCTED IN PARK ONLY WITH EMERGENCY BRAKE
Enter Self-Test Diagnostics by depressing the
speed control OFF switch while turning the ignition key ON, ensuring engine
does not start and is not running. The speed control indicator on the
instrument panel will flash once to indicate that speed control module entered
the diagnostic mode. Five additional flashes at this point indicate a
speed control servo. Release the OFF switch.
Press the remaining switches in this sequence:
ON, RESUME, COAST, and SET/ACCEL. IF THE "ON" SWITCH IS NOT DEPRESSED WITHIN
5 SECONDS AFTER ENTERING THE
DIAGNOSTICS MODE, THE MODULE TIMES OUT AND THE PROCEDURE MUST BE STARTED OVER.
The speed control indicator lamp will flash as each switch is depressed. Press
each switch in the sequence immediately after the indicator light goes out for
the previous switch.
A lamp flash with the last button (SET/ACCEL)
indicates that the STATIC test passed. If the lamp does not flash with the
last button and there are no additional flashes of the lamp, the switch is
defective. If the lamp does not flash with the last button, and additional
flashes occur, follow the chart below for trouble codes:
2 Flashes - BPP defective, circuit is
defective, brake applied.
3 Flashes - Deactivator switch is open or
4 Flashes - Vehicle speed out of range.
Immediately after the static test has passed,
speed control servo will then perform a dynamic test automatically by
actuating the throttle lever from 1 mm
to 10 mm of travel from the idle
position. During the dynamic throttle pull, observe throttle movement to
witness any binding or sticking of actuator cable, proper connection of
actuator cable to throttle lever, and ensure throttle returns back to idle
position. If improper connection and/or binding or sticking of actuator is
observed, go to Symptom Chart.
See: Symptom Chart
Return ignition switch to the OFF position and
proceed to Symptom Chart.
See: Symptom Chart
Self-Test Diagnostics must be performed before
proceeding to Symptom Chart.
Use Rotunda 73 Digital Multimeter 105-R0051 or
equivalent to perform pinpoint tests.
New speed control diagnostic software is
available in version 12 or higher for New Generation STAR
(NGS) Tester or equivalent 418-F048
(007-00500). When using this software it is necessary to use Next Generation
Speed Control Adapter 007-00586 with NGS Tester.
My Thanks to the usual suspect.