Questions and Answers

Volvo 740 GLE Won't Start Unless Shot Q. Vincent I have a 1991 Volvo 740 gle non-diesel and non-turbo. The problem I have is in order to start my vehicle I have to spray ether into the Mass Air Flow sensor with the engine hot or cold. Once it start it runs fine until I shut it off and I have to repeat the process. Thanks, Mike

A. The first thing we have to do is check for codes. It may be due to a bad PCM or Coolant Temperature Sensor. Once we know what the codes are, we can go from there. To get the codes:

Open the diagnostic socket cover and connect the selector cable into the appropriate socket.

1. For fuel injection trouble shooting use socket 2 (of the 6 available).
2. For ignition trouble shooting use socket 6 (of the 6 available).

Turn the ignition ON.
Enter control function #1 by pressing the button once for at least 1 second, but not more than 3 seconds.

	Watch the light diode and count the number of flashes in the three flash series indicating a fault code. Make note of the fault codes. If no fault codes are received by the diagnostic unit, the diode will flash 1-1-1 and the fuel injection system is okay. Retrieve all fault codes stored in the ECU memory by depressing the button a second and third time until the first code is repeated. This means there are no more other codes stored. Remember, all vehicles except California market cars can store only three codes. After the repairs, the vehicle must be driven in order to find and set new codes.

Fault Code Chart For Fuel Injection ECU:
1-1-1:	No faults, fuel injection system is okay.
1-1-2:	Fault in fuel injection ECU
1-1-3:	Fault in fuel injector (broken lead, clogged...)
1-2-1:	Signal to/from Mass Air Flow sensor faulty
1-2-3:	Signal missing to/from coolant temperature sensor, possible short circuit
1-3-1:	Ignition system RPM signal missing
1-3-2:	Battery voltage too low or high
1-3-3:	Throttle position switch ; idle setting faulty, possible short circuit
2-1-2:	Oxygen sensor (lambda sond) signal missing or faulty
2-1-3:	Throttle position switch ; full load setting faulty, possible short circuit
2-2-1:	Oxygen sensor (lambda sond) not operating
2-2-3:	Signal missing to/from idle air valve
2-3-1:	Self-adjusting oxygen sensor (lambda sond) not operating
2-3-2:	Self-adjusting oxygen sensor (lambda sond) not operating
3-1-1:	Signal missing from speedometer
3-1-2:	Signal missing from knock related fuel enrichment
3-2-2:	Hot wire "burn-off cleaning" in Mass Air Flow sensor not operating

Fault Code Chart For Ignition ECU:
1-1-1:	Ignition system okay
1-4-2:	Fault in ignition ECU
1-4-3:	Knock sensor faulty
1-4-4:	Missing air flow meter signal
2-1-4:	Crankshaft position/speed sensor faulty
2-2-4:	Coolant temperature sensor faulty
2-3-4:	Throttle position sensor idle function faulty
2-4-1:	EGR system faulty
4-1-3:	Temperature sensor signal

Clearing Fault Codes:

1. Turn ignition switch ON (if not already in the ON position).
2. Read the fault codes again.
3. Depress the button for more than 5 seconds. Release the button. After 3 seconds the diode should light up.
4. While the diode is still illuminated, depress the button again for more than 5 seconds. After releasing the button the diode should go out.
5. Check that the memory is erased by depressing button for 1 second but not more than 3 seconds. Diode should flash code 1-1-1.
6. Test drive vehicle and recheck for new fault codes. If code 1-1-1 flashes, system is operating correctly. If new fault codes appear, repeat entire control function #1 procedure again.