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TaurusKev

Howto: Diagnose/troubleshoot Gen 1/gen 2 Vacuum-Powered Cruise Control

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This is a long one... Will break up into multiple posts here. This is intended to troubleshoot intermittent or non-functional cruise/speed controllers on Gen 1/Gen 2 Bulls. This may work for other Ford models that used a vacuum system.

 

 

Component Location and name and callouts:

 

speedcontrolcomploc.png

 

 

-----------------------------------------------------------------------------
|    Item    |     Part Number  |               Description               |
-----------------------------------------------------------------------------
|     1      | 9C490                 | Vacuum Outlet Manifold             
|     2      | 12226                 | Check Valve to Speed Control Vacuum Reservoir Hose (Bulk Hose)
|     3      | --                         | Driver's Side Shock Tower (Part of Unibody)
|     4      | 9C735                 | Speed Control Servo                        
|     5      | 9A825                 | Speed Control Actuator                 
|     6      | N611057             | Screw                                  
|     7      | 9A758                 | Accelerator Cable                  
|     8      | 12226                 | Speed Control Dump Valve Hose (Bulk Hose)                              

-----------------------------------------------------------------------------------------------------

 

 

speedcontdiag.png

 

Cruise Control Test:

A1    CHECK CONNECTIONS
Check all electrical and vacuum connections.
Are all connections OK?

Yes
GO to «A2».


No
SERVICE or REPLACE as required.


 

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A2    CHECK STOPLIGHTS
Apply brake pedal (2455).
Are stoplights operating properly?

Yes
GO to «A3».

No
SERVICE stoplight circuits.

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A3    CHECK SPEED CONTROL ACTUATOR CABLE CONNECTION TO THROTTLE BODY AND SPEED CONTROL SERVO
Check to see if speed control actuator cable is attached to throttle body accelerator linkage.
Check to see if speed control actuator cable is attached to speed control servo (9C735) linkage.
Is speed control actuator cable attached to both?

Yes
GO to «A4».

No
ADJUST or SERVICE as required.

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A4    CHECK LINKAGE OPERATION
Check the throttle linkage for proper operation.
Does linkage operate properly?

Yes
GO to «A5».

No
SERVICE as required.

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A5    CHECK VACUUM HOSES
Check to see if:
* Vacuum supply hose is tightly connected to VAC port on speed control vacuum valve (9C793) and to vacuum outlet manifold (9C490), and free of cuts, cracks and kinks.
 
* Vacuum hoses are tightly connected between speed control vacuum valves and speed control servo, and free of cuts, cracks and kinks.
 
* Vacuum hose is tightly connected between speed control vacuum valve and speed control vacuum reservoir (9E799), and free of cuts, cracks and kinks.
 
* Speed control dump valve hose is tightly connected to the speed control servo and speed control dump valve (9C727), and free of cuts, cracks and kinks.

Are all checks successful?

Yes
GO to «A6».

No
SERVICE as required.

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A6    CHECK THE SPEED CONTROL VACUUM VALVE AND SPEED CONTROL VACUUM RESERVOIR

 

Disconnect the hose between speed control vacuum valve and speed control servo, at the speed control servo end.
 
-  Apply 60.6 kPa (18 in-Hg) vacuum to open end of hose.

 

- Can vacuum be pumped to and held at 60.6 kPa (18 in-Hg) vacuum?

Yes
GO to «A7».

No
SERVICE as required.

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A7    CHECK SPEED CONTROL DUMP VALVE
Disconnect the hose (white stripe) between speed control dump valve and speed control servo at the speed control servo end.
-  Apply 60.6 kPa (18 in-Hg) to open end of hose.

-  Can vacuum be pumped up and held at 60.6 kPa (18 in-Hg) vacuum?

Yes
GO to «A8».

No
SERVICE or ADJUST as required.

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A8    PERFORM SPEED CONTROL ACTUATOR SWITCH TEST

CAUTION:
Do not use a test lamp to perform the following tests as excessive current draw will damage electronic components inside the speed control amplifier (9D843). Use only a voltmeter of 5,000 ohm/volt rating or higher.

Disconnect the 6-pin connector at the speed control amplifier assembly.


1.    Connect a voltmeter across Circuit 151 (LB/BK) and ground. With ignition in the ON position, depress the ON button and check for battery voltage.
 
2.    Connect an ohmmeter between Circuit 151 (LB/BK) and ground.
 
3.    Rotate the steering wheel (3600) throughout its full range of motion while making the following checks.

a.    Depress the OFF button and check for a reading between 0 and 1 ohm.
 
b.    Depress the SET/ACCEL button and check for a reading between 714 and 646 ohms.
 
c.    Depress the COAST button and check for a reading between 126 and 114 ohms.
 
d.    Depress the RESUME button and check for a reading between 2310 and 2090 ohms.

If resistance values are above the allowable limits, check the air bag sliding contact (14A664) as follows:

(1)    Disconnect air bag sliding contact at the base of steering column. Check for battery voltage on Circuit 6 (Y/LG). If there is no battery voltage, go to Step 2, then go to Step 4, otherwise go to Step 4 directly.
 
(2)    Disconnect horn relay. Check for battery voltage at the horn relay connector in Circuit 40 (LB/W). If there is no battery voltage, check 20A fuse, and Circuit 40 (LB/W).
 
(3)    With the horn relay disconnected, apply 12V voltage to Pin 86 of the horn relay and bracket (13853). Check for 12V voltage at Pin 85 of the horn relay and bracket. If the voltage at Pin 85 of the horn relay and bracket is not approximately equal to 12V, replace the horn relay and bracket.
 
(4)    Disconnect speed control actuator switch (9C888) and measure resistance across each of the air bag sliding contact windings between the air bag sliding contact connector at the base of steering column and speed control switch connector in the steering wheel. Each resistance reading should be between 0.25 and 0.5 ohms.
 
(5)    Check continuity in Circuit 151 (LB/BK) between speed control actuator switch and speed control amplifier. Check continuity to ground in Circuit 57 (BK).

Reconnect the 6-pin connector at the speed control amplifier.
 

ON Circuit

Turn ignition switch (11572) to RUN. Connect voltmeter between Circuit 296 (W/P) and ground in 6-pin connector at speed control amplifier. Voltmeter should read battery voltage.

If battery voltage is not present, check the fuse and service as required.

Connect voltmeter between Circuit 151 (LB/BK), and ground in 6-pin connector at speed control amplifier. The voltmeter should read battery voltage when the ON switch on the steering wheel is pressed and held. If voltage is not available perform Speed Control Actuator Switch Test.

Release the ON button. The voltmeter should read approximately 7.8 volts. The voltage should remain at approximately 7.8 volts until one of the speed control buttons is pressed and held. If the meter reads zero, check the ground connections on the speed control amplifier (either black wire on the 6-pin connector). If there is still no ground on the speed control amplifier, check the system ground connection, and wiring. Also check the 20-amp fuse and/or substitute (but do not install) a known good speed control amplifier and recheck for a properly operating ON circuit.
 

OFF Circuit

With the ignition switch in RUN and the voltmeter connected between Circuit 151 (LB/BK) on the 6-pin connector and ground, press and hold the OFF switch on the steering wheel. The voltmeter should indicate zero volts. If the voltage does not drop to zero, perform Speed Control Actuator Switch Test. If the switches check OK, substitute a known good speed control amplifier and recheck the OFF circuit as outlined.
 

SET/ACCEL Circuit

With the ignition switch in RUN and the voltmeter connected between Circuit 151 (LB/BK) in the 6-pin connector and ground, press and hold the SET/ACCEL button on steering wheel. Voltmeter should indicate approximately 4.5 volts. Rotate the steering wheel back and forth and watch the voltmeter for fluctuations. If the voltage varies more than 0.5 volt, perform the Speed Control Actuator Switch Test.
 

COAST Circuit

With the ignition switch in RUN and the voltmeter connected between Circuit 151 (LB/BK) in the 6-pin connector and ground, press and hold the COAST button on steering wheel. The voltmeter should indicate approximately 1.5 volts.
 

RESUME Circuit

With the ignition switch in RUN and the voltmeter connected between Circuit 151 (LB/BK) in the 6-pin connector and ground, press and hold the RESUME button on the steering wheel. The voltmeter should read approximately 6.5 volts.

NOTE:
Do not substitute a good speed control amplifier until the speed control servo test has been successfully completed.

If all the circuits check OK, perform the speed control servo test and substitute a known good speed control amplifier.

-  Are tests successful?

Yes
GO to «A9».

No
SERVICE circuits or REPLACE speed control actuator switch (9C888) or air bag sliding contact (14A664).

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A9    CHECK SPEED CONTROL SERVO
Separate speed control servo from speed control amplifier (9D843).
 
-  Connect the Circuit 144 (O/Y) lead of the speed control servo to the battery positive terminal.
 
-  Connect the Circuit 146 (W/PK) lead of the speed control servo to ground, and momentarily touch the Circuit 145 (GY/BK) lead of the speed control servo to ground.
 
-  The throttle actuator arm should pull in and the engine speed should increase. The arm should hold in that position or slowly release.
 
-  When Circuit 146 (W/PK) is removed from ground the throttle actuator arm should release.

Does speed control servo operate properly?

Yes
GO to «A10».

No
REPLACE speed control servo.

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A10    CHECK VSS
-  Disconnect 6-pin connector at speed control amplifier.
 
-  With an ohmmeter measure resistance between Circuit 150 (DG/W) VSS signal) and Circuit 57 (BK/ground).

 

 Is the resistance approximately 200-300 ohms?

Yes
GO to «A11».

No
REPLACE vehicle speed sensor (VSS) (9E731).

 

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A11    CHECK SPEED CONTROL AMPLIFIER


l    Disconnect 8-pin connector at speed control amplifier.
 
l    Measure resistance between the following circuits of the connector and check against the normal values.
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³                         Circuits                          ³  Normal Resistance  ³
ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´
³ 144 (O/Y) and 145 (GY/BK)                                 ³         40-75 ohms  ³
³ 144 (O/Y) and 146 (W/PK)                                  ³       100-150 ohms  ³
³ 147 (P/LB) and 148 (Y/R)                                  ³       20k-30k ohms  ³
³ 147 (P/LB) and 149 (B/LG)                                 ³       40k-60k ohms  ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ

l    Are all resistance values within limits?

Yes
INSTALL a new speed control amplifier.

No
EXAMINE all connectors carefully for proper contact. SERVICE as required. REMOVE substitute speed control amplifier.

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