Circuit Test 3.0L

NOTE: See SYMPTOM TABLE (3.0L) before proceeding.

SYMPTOM

Symptom

Circuit Test Step

Will Not Set

1 & 3

Intermittent Operation

RESUME, COAST or ACCEL Switches Inoperative

Speed Fluctuates

1 & 3

Will Not Disengage With Brakes

Will Not Disengage With Clutch

Abnormal Operation In COAST Or ACCEL

⁽¹⁾

⁽¹⁾	To service slip ring and brush assembly, see the STEERING COLUMN SWITCHES article in the ACCESSORIES/ SAFETY EQUIP Section for removal of steering wheel.

Check Vacuum Supply: Start engine. Connect vacuum gauge to servo vacuum hose. Increase engine speed to 2000 RPM. If at least 2.5 in. Hg vacuum is present, go to next step. If 2.5 in. Hg vacuum is not present, repair vacuum hose.
Check Servo Cable Deflection: Cable should have .039-.118" (1-3 mm) of deflection. Adjust cable as necessary. If deflection is correct, check vacuum dump valve. Vacuum dump valve should hold 5-10 in. Hg vacuum. If dump valve operation is not correct, check vacuum hose, and adjust or replace dump valve.
On 1992 models, check 20 amp. brakelight and 15 amp. meter fuses. Replace as necessary. If fuses blow after replacement, locate and repair short to ground. On all models, if fuses are okay, check brake on/off switch. Disconnect amplifier connector. Turn ignition on. Measure voltage on White/Green wire (on automatic transmission) and Blue/Orange wire (on manual transmission) of 8-pin amplifier connector.
Voltage should be greater than 10 volts with brakes applied. Voltage should be less than one volt with brakes released. On automatic transmission models, if voltage is not correct, repair White/Green wire. If voltage is okay, go to step 7). On manual transmission models, if voltage is not okay, go to next step. If voltage is okay, go to step 6).
Turn ignition on. Measure voltage at clutch switch on White/Green wire. Voltage should be greater than 10 volts with brake applied and less than one volt with brake released. If voltage is not correct, repair White/Green wire. If voltage is okay, go to next step.
Check Clutch Switch: Disconnect amplifier connector. Turn ignition on. Measure voltage on Blue/Orange wire of 8-pin amplifier harness connector. Apply brake and clutch. Voltage should be greater than 10 volts with clutch released and less than one volt with clutch applied. If voltage is okay, go to next step. If voltage is not okay, repair Blue/Orange wire.
Check Power To Amplifier: Disconnect amplifier connector. Turn ignition on. Measure voltage on Blue/Black wire of 6-pin amplifier connector. If 10-14 volts are present with cruise control on and less than one volt is present with cruise control off, go to next step. If not, repair Blue/Black wire or cruise control switch.
Check Ground: Turn ignition off. Disconnect amplifier connector. Measure resistance between Black wire (Black/Blue wire on vehicles with warning chime) of 6-pin amplifier connector and ground. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair Black or Blue/Black wire to ground.
Check Control Switches: Turn ignition off. Disconnect amplifier connector. Measure resistance between Blue wire of 6-pin amplifier connector and ground. Actuate switches one at a time. See CONTROL SWITCH RESISTANCE table. If resistance is correct, go to next step. If resistance is not correct, repair Blue wire, switch ground or replace switch.

Check Servo: Turn ignition off. Disconnect amplifier. Measure resistance between amplifier harness wires. See appropriate SERVO RESISTANCE table. If resistance is correct, go to next step. If resistance is incorrect, repair faulty wires or replace servo.

CONTROL SWITCH RESISTANCE

Switch	Resistance
Set/Accel	646-714 Ohms
Coast	114-146 Ohms
Resume	2090-2310 Ohms

1991 SERVO RESISTANCE

Wires	Resistance
Green & Green/White	40-70 Ohms
Green/White & Green/Black	110-140 Ohms
Red & Red/White	40,000-60,000 Ohms
Red/Black & Red/White	20,000-30,000 Ohms

1992 SERVO RESISTANCE TALBE

Wires	Resistance
Green & Green/White	40-70 Ohms
Green/White & Green/Black	140-220 Ohms
Green& Green/Black	100-150 Ohms
Red & Red/White	40,000-60,000 Ohms
Red/Black & Red/White	20,000-30,000 Ohms

Shift transmission into Neutral. Apply parking brake and block wheels. Start engine. Turn cruise control on. Jump Green wire of amplifier harness connector to battery positive. Jump Green/Black wire of amplifier harness connector to battery negative. Momentarily jump Green/White wire of amplifier harness connector to battery negative.
If engine speed does not increase when Green/White wire is momentarily grounded and return to idle when disconnected, replace servo. If engine speed increases when Green/White wire is momentarily grounded and returns to idle when disconnected, turn ignition off. Go to next step.
NOTE: On vehicles with analog clusters, Vehicle Speed Sensor (VSS) is located in cluster with a Green/Red wire. On vehicles with electronic clusters, VSS is located in transaxle with a Yellow/White wire.
On 1991 models, to check VSS, turn ignition off. Disconnect VSS connector. Measure resistance between sensor terminals. If resistance is not 180-220 ohms, replace VSS. If resistance is 180-220 ohms, repair Black/Red or Black/Blue wires between sensor, ECA and amplifier. If wires are okay, replace amplifier.

On 1992 models, to check VSS, connect voltmeter between Black/Red and Black/White wires of amplifier harness connector. Voltmeter should be in AC volt setting. Drive vehicle at various speeds and verify appropriate voltages are present. See SPEED SENSOR VOLTAGE table. If voltages are correct, replace amplifier. If voltages are not correct, go to next step.

SPEED SENSOR VOLTAGE

Speed (MPH)	Voltage
5	.8
10	1.2
15	1.6
20	2.0
25	2.3
30	2.6
35	3.0
40	3.3
45	3.5
50	3.8
55	4.02

Check Vehicle Speed Sensor (VSS) Continuity On all models, turn ignition off. Disconnect VSS, amplifier and ECA. Measure resistance on Black/Red and Blue/White wires between VSS, amplifier and ECA harness connectors. If resistance is less than 5 ohms, replace VSS. If resistance is greater than 5 ohms, repair faulty wire.