Cruise Control - Testing & Tools
89saab05FILE IN VOL.
S.I. Man I
SEC. PG.
A-3 112
ISSUE: 02/89-1115
SUPERSEDES: 03/87-953
SUBJECT: TESTING THE CRUISE CONTROL SYSTEM
APPLICATION: ALL 900 MODELS WITH THE HELLA CRUISE CONTROL
Figure 1:
Figure 1:
The cruise control tester (Figure 1) can be used to aid in fault-tracing the cruise control system on Saab 900 models. The tester connects to the cruise control wiring harness and checks the vacuum pump and electrical switches (Figure 2).
Note that the cruise control speed sensor was changed on 1989 900 models. This bulletin reflects this speed sensor change. Any areas where the text has been revised are highlighted by a bold black line to the left of the text. Failure to use this revised procedure may result in permanent damage to your tester.
The cruise control tester is a required special tool.
Figure 2:
Test Procedure
Tool Required:
Cruise Control Tester P/N 85 80 078
CAUTION
NEVER DRIVE 1989 900 MODELS WITH THE CRUISE CONTROL TESTER CONNECTED. THIS MAY CAUSE PERMANENT DAMAGE TO THE TESTER.
1. Unplug the connections from the control unit (one eight-pole and one single-pole) and connect them to the tester (Figure 2).
2. Move the CRUISE CONTROL switch to "Off" and switch on the ignition. Light emitting diodes (LED) 1, 3, and 5 should light up.
Fault-tracing:
- If LED 1 fails to light up, check the power supply to the control unit plug.
- If LED 3 fails to light up check the pedal switches the wiring.
- On 900 models up to 1988: if LED 5 fails to light up, check the speedometer sensor on the speedometer and its wiring. LED 5 should light up if the car is moving or stationary.
- On models from 1989: use step 11 to test the speed sensor after removing the cruise control tester from the car.
3. Depress the clutch pedal. LED 3 should go out. Release the clutch pedal (LED lights up). Then depress the brake pedal, LED 3 should go out.
Fault-tracing:
- Check the operation and adjustment of the corresponding pedal switch and wiring for short circuits.
4. Switch the CRUISE CONTROL switch to "On". LED 9 should light up.
Fault-tracing:
- Check the switch and its wiring.
5. Depress the SET SPEED button. LED 2 and 6 will light up in two steps and stay illuminated while the button is depressed.
Fault-tracing:
- Check the switch and its wiring.
6. Depress the RESUME button. LED 6 should stay on as long as the button is depressed.
Fault-tracing:
- Check the button/switch and its wiring.
7. Depress the VENT button on the tester. You should hear the Cruise Control pump "click" as it operates.
Fault-tracing:
- Check the valve and its wiring.
8. Depress the PUMP button on the tester. You should hear the pump operate.
Fault-tracing:
- Check the pump and its wiring.
9. Depress the PUMP button and observe the throttle arm on the throttle housing. The throttle should open.
When the VENT button is depressed (or the clutch or brake pedal) the throttle arm should release.
Fault-tracing:
- Check the vacuum system.
10. Unplug the vehicle wiring harness connections from the tester and reconnect them to the control unit.
CAUTION
NEVER DRIVE 1989 900 MODELS WITH THE CRUISE CONTROL TESTER CONNECTED. THIS MAY CAUSE PERMANENT DAMAGE TO THE TESTER.
11. On 900 models from 1989 up, check the operation of the speed sensor using the upshift light.
Manual Transmission - Warm up the car and check that the upshift illuminates during the proper driving cycle. This indicates a functioning speed sensor.
Automatic Transmission - Temporarily install the bulb and socket from the extreme right-hand warning lamp into the blank upshift light socket on the left side of the instrument cluster.
Warm up the car, select position 1 of the gear selector and drive the car at light throttle. The upshift light should illuminate at approximately 2,500 rpm, indicating a functioning speed sensor. Remove the bulb/socket and replace it in its original location.
The wiring should be checked for continuity between the speed sensor and the electronic control unit to ensure that the speed sensor signal is reaching the ECU.
12. If no faults are found during these tests and a cruise control fault still exists, the electronic control unit is probably defective. Replace the control unit.