Question about 1991 Plymouth Acclaim

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Hissing from speed control servo - 1991 Plymouth Acclaim

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It is leaking vacuum replace it.

Posted on Nov 05, 2012


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My cruise control does not work on 1994 Ford 150. Fuse is fine, where to look next? Thank you

Which fuse ? There are two that supply B+ to the speed control servo ! One is located in the under hood fuse box and the other in the fuse panel inside the vehicle > The fuse may look fine but is there B+ voltage across the fuse . Check it with a volt meter . Check B+ voltage at the speed control servo , Black with yellow trace and P/O wire , what ever color that is . Is there B+ at the control switch ? The speed control servo supply's voltage to the cruise control switch . You can check it at the speed control servo as well . They could be videos on youtube showing how to test it .
Diagnose cruise control failure on 1993 Ford 150

May 31, 2017 | Ford Cars & Trucks

1 Answer

2002 f150 cruise inop shows code 3?

  • 3 flashes - deactivator switch is open or circuit defective.
    • Flash code 3 - deactivator switch circuit failure
    • Central junction box (CJB) fuse 13 (20A).
    • Circuitry.
    • Deactivator switch.
    • Speed control servo.
    • Go To Pinpoint Test H .
    Speed Control Servo C122
    Measure the voltage between the speed control servo C122 pin 9, circuit 307 (BK/YE), harness side and the speed control servo C122 pin 10, circuit 57 (BK), harness side.
    • Is the voltage greater than 10 volts?
    Yes INSTALL a new speed control servo. REFER to Speed Control Servo in this section. REPEAT the self-test.

    Deactivator Switch C1025
    Measure the voltage between the deactivator switch C1025, circuit 10 (LG/RD), harness side and ground.
    • Is the voltage greater than 10 volts?
    Yes GO to H3 .

    No REPAIR the circuit. REPEAT the self-test. H3 CHECK CIRCUIT 307 (BK/YE) FOR AN OPEN Measure the resistance between the speed control servo C122 pin 9, circuit 307 (BK/YE), harness side and the deactivator switch C1025, circuit 307 (BK/YE), harness side.
    • Is the resistance less than 5 ohms?
    Yes INSTALL a new deactivator switch. REFER to Speed Control Deactivator Switch in this section. REPEAT the self-test.

    No REPAIR the circuit. REPEAT the self-test.

Nov 23, 2016 | 2002 Ford F-150

1 Answer

My brake pedal will not budge, and a hissing noise present when running

The stop lights won't go out until the pedal is depressed, as there is a switch which is activated by the pedal.

A hard brake pedal is probably caused by a defective servo. The hissing noise is probably an air leak in the servo.

Switch the engine on, open the bonnet (the hood..) and see if you can locate the hissing - that'll probably be in the brake servo area.

If you don't know what a brake servo looks like here is a generic image:


Jan 27, 2016 | 1989 GMC Sierra

2 Answers

Where can I locate the crank sensor on a grand caravan 3.3 lt 2001 sport

Remove battery.
Remove the battery tray.
Disconnect the speed control vacuum harness from servo.
Remove the speed control servo and bracket and reposition. Disconnect the electrical connector.
Disconnect the electrical connector from crankshaft sensor.
Remove the mounting bolt.
Remove sensor

Oct 07, 2012 | Cars & Trucks

1 Answer

Hi renault scenic 2l auto 2002. another common problem.

hissing noise is a leaking diaphram inside power brake have to replace the power brake booster.

Sep 18, 2012 | Renault Megane Cars & Trucks

1 Answer

Volvo s90 cruise control doesn't run at a constant speed

You may have a failing Cruise Control Servo. Have the servo tested by a Volvo or other qualified service center.

Apr 22, 2012 | 1998 Volvo S90

2 Answers

My cruise control does not work on my 2003 Ford Focus

Hi Fred,

There are several things that can cause your cruise control to not function. Anything from a bad speed sensor to a faulty speed control servo. It is impossible to tell you what is wrong without diagnosing your speed control system. Here is a quote from the vehicle manufacturer regarding this issue:

"Start by running speed control servo integrated self test diagnostics. The servo has integrated self test diagnostics which is a key tool in quickly and accurately diagnosing speed control system faults. Self test diagnostics are also the basis for starting speed control trouble shooting."

Please note that a diagnostic scan tool capable of accessing the speed control data is required for performing this task.

Oct 15, 2011 | 2003 Ford Focus

1 Answer

What are the compute codes 24 and 34 on a 1988 Dodge Daytona

Code 24 is Throttle Position Sensor,

This is locared on the right side of the throtle body accross from the throtle linkage there is 2 torx screws holding in place and one wire end to disconect install reverse from instructions

code 34 Speed Control Servo Circuit. No check engine light will post.
Your cruse control servo is not turning on and off like it should.
I would do the tps first then disconect the batery for 5 minn then re check the car for codes, the tps might be messing with the speed control servo.
Let me know if i can help more!

Jul 19, 2010 | 1988 Dodge Daytona

1 Answer

I have a 2001 Ford F-350 V-10 cruise control stopped working

Speed Control The speed control system consists of the following components:
  • anti-lock brake control module
  • brake pedal position (BPP) switch
  • clutch pedal position (CPP) switch or jumper
  • deactivator switch
  • speed control actuator switches
  • speed control servo
  • speed control actuator cable
  • speed control indicator
  • brush assembly (Motorhome vehicles only)
  • control and spring brush assembly (Motorhome vehicles only)
  • Principles of Operation
    The speed control system is designed to maintain vehicle speed above 40 km/h (25 mph). After the ON switch is depressed, depressing the SET/ACCEL or COAST switch will activate the speed control servo. To increase a set speed, either depress and hold for continuous acceleration, or momentarily tap the SET/ACCEL switch for 1.6 km/h (1 mph) acceleration increments. To decrease a set speed, depress and hold the COAST switch until the target speed is reached, or momentarily tap the COAST switch for 1.6 km/h (1 mph) deceleration increments. When the speed control system has been disabled by tapping the brake pedal, the RESUME switch can be depressed and the vehicle will return to the original set speed if the vehicle is traveling over 40 km/h (25 mph) and the OFF switch has not been depressed.
    NOTE: The deactivator switch is provided as an additional safety feature. Normally, when the brake pedal is depressed, an electrical signal from the brake lamp circuit to the speed control servo will deactivate the system. Under increased brake pedal effort, the deactivator switch will open and remove power to the speed control servo, releasing the throttle independently of the speed control servo.
    NOTE: The air bag sliding contact provides the electrical interface between the steering column wiring and the speed control actuator switches in the steering wheel.
    The inputs to the speed control servo are:
    • vehicle speed signal
    • speed control actuator switches
    • brake pedal position (BPP) switch
    • clutch pedal position (CPP) switch (if equipped)
    • deactivator switch
    The outputs of the speed control servo are:
    • speed control indicator (Excursion and Super Duty)
    • speed control cable controlling the throttle position
    Inspection and Verification
    NOTE: If any concerns are noted with the speedometer or horn, address those concerns by referring to their associated sections before continuing speed control diagnosis.
    NOTE: When in speed control mode, initial depression of the clutch pedal may cause a normal momentary increase of engine rpm.
    NOTE: If the vehicle is a diesel, refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
    1. Verify the customer concern by operating the speed control system.
    1. Visually inspect for obvious signs of mechanical and electrical damage.

    Visual Inspection Chart Mechanical Electrical
    • Speed control cable
    • Speed control cable not attached to throttle
    • Central junction box (CJB) Fuse:
      • 6 (15A) (Excursion)
      • 8 (10A) (Motorhome)
      • 13 (20A) (Excursion, Super Duty)
      • 15 (5A) (Super Duty, Excursion)
      • 28 (10A) (Super Duty, Motorhome)
    • Speed control actuator switches
    • Brake pedal position (BPP) switch
    • Clutch pedal position (CPP) switch (if equipped)
    • Deactivator switch
    • Speed control servo
    • Wiring
    • Loose, corroded, or dirty connections
    • Bulb (Excursion and Super Duty)

    1. If the fault is not visually evident, go to the Self-Test Diagnostics - Excursion or Super Duty (Excursion, Super Duty), or verify the symptom and proceed to the Symptom Chart (Motorhome).
    2. Self-Test Diagnostics - Excursion, Super Duty
      WARNING: This test is a key on engine off (KOEO) test only that is conducted in park only with emergency brake fully engaged.
      1. Enter Self-Test Diagnostics by depressing the speed control OFF switch while turning the ignition key ON, making sure the 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 DEFECTIVE SPEED CONTROL SERVO. Release the OFF switch.
      1. Press the remaining switches in this sequence: ON, RESUME, COAST and SET/ACCEL.
        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.
      1. 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, CPP switch or jumper (if equipped).
      • 3 Flashes - Deactivator switch is open or circuit defective.
      • 4 Flashes - Vehicle speed signal is out of range or circuit is defective.
      1. Immediately after the STATIC test, the speed control servo does a DYNAMIC test by automatically actuating the throttle lever from 8 mm (0.315 in) to 12 mm (0.472 in) of travel from the idle position. During the DYNAMIC throttle pull, observe throttle movement to witness any binding or sticking of the speed control cable and correct connection of speed control cable to throttle lever. Make sure the THROTTLE RETURNS BACK TO IDLE POSITION.
      1. Return ignition switch to the OFF position and proceed to the Symptom Chart.

Dec 28, 2017 | 2001 Ford Escape

1 Answer

Change timing belt and idle speed servo kit.

send me your e-mail so i can send to you full repair instruction and picture

Sep 02, 2008 | 2004 Mitsubishi Lancer

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