964 Oil Temperature Sensor

Air temperature at center nozzle vs. ambient temperature

Ambient temperature

1357-87

Diagnosis / Troubleshooting

The heater and/or air conditioner can be checked with a 9288 System Tester or 9268 Tester. The 9268 tester is connected in the 19-pin diagnosing socket with help of adapter leads 9268/2 and 9288/1.

Reading Fault Memory

9288 System Tester: see Repair Group 03, Self-diagnosis.

9268 Tester: see information brochure on diagnosing DME, LH-EZK.

Information for 9268 Tester:

The fault memory of the DME control unit must be read first. The fault memory of the heater and/or air conditioner can be read only after 1500 (no faults stored) or 1000 (end of output) is displayed.

If the control lamp for the airbag system indicates a fault, flashing code diagnosis with the 9268 Tester will not be possible. Diagnosing is only possible with a 9288 System Tester.

Explanation of Four Digit Fault Codes:

1st digit: 8 = Heater and/or air conditioner

2nd digit: 1 = Fault existing at moment

2 = Fault not existing at moment

3rd digit ?

This diagnosing/troubleshooting plan is based on the contents of the fault memory.

Paths not covered by self-diagnosis can be diagnosed with conventional means (Test Point 1 in following Fault List).

Troubleshooting requires that the person testing

. knows the location of components, function and interrelation of the systems being tested (model information),

. is capable of reading and evaluating Porsche wiring diagrams,

. knows the function of circuits and relays, and

. knows how to operate and read testers such as oscilloscope, voltmeter, ohmmeter and ammeter, important:

If a faulty component appears in the display of a tester or in the Fault List, the fault does not have to be in the displayed component, but instead could also be in the concerned control unit or connecting leads (paths) between the component and control unit. No troubleshooting may be carried out in the form of disconnecting plugs and so on before reading the fault memory, since this could be stored as a fault in the fault memory.

Note

Displayed

Fault does not exist, this could mean:

- Fault does not exist at time of testing (loose contact) Remedy: Path checked by visual inspection

- Conditions, with which the fault had occured, are not given (e.g. ignition not turned on, AC button not pressed)

Remedy: Compliance with the conditions displayed in the tester Signal unplausible:

- The control unit cannot recognize wheter there is a short, break or seizure of an electric motor.

Temperature Sensor Values

Left and Right Mixing Chambers at: 0°C ( 32° F) 25°C ( 77° F) 50°C (122° F)

Rear Fan at 0°C (32°F) 25°C (77°F) 50°C (122° F)

Oil Cooler at 60°C (140° F) 85°C (185° F) 100°C (212° F)

Criteria for canceling the diagnostic operation

1. Vehicle speed > 0 mph

2. RH mixing chamber temperature > 80°C

3. LH mixing chamber temperature > 80° C

Criteria for starting the diagnostic operation

1. Vehicle speed = 0 mph

2. RH mixing chamber temperature < 80°C

3. LH mixing chamber temperature < 80°C

5. Oil temperature < 105°C

Fault, Fault Code Possible Causes, Elimination, Remarks

Test Point 1

Power supply to heater/air conditioner regulator

K1 - term. 31 K2 - term. 30 G29 - term. X G35 - term. 15 G17 - term. 58 b (light) check

Test Point 2

Inside temperature sensor Replace heater/air conditioner regulator. Fault Code 8 _ 11

Test Point 3

Left mixing chamber temperature sensor Fault Code 8 _ 12

Test Point 4

Right mixing chamber temperature sensor Fault Code 8 _ 13

Test Point 5

Evaporator temperature Measure resistance between G 18 and G 22. Check both electric sensor leads against ground.

Fault Code 8 _ 14

Test Point 6

Rear fan temperature sensor Measure resistance between G 10 and G 18. Check both electric Fault Code 8 15 leads against ground. Note that the electric leads run via two plugs

Measure resistance between G 18 and G 23. Check both electric leads against ground.

Measure resistance between G 18 and G 24. Check both electric leads against ground.

Fault, Fault Code Possible Causes, Elimination, Remarks

Test Point 7

Oil cooler temp, sensor Measure resistance between G 12 and G 18. Check both electric

Fault Code 8 21 leads against ground. Note that the electric leads run via plug T 34.

Test Point 8

Defrost flap motor 1. Check voltage between G 18 (negative) and G 26 (positive).

Fault Code 8 22 Display: 0.2 - 5 volts depending on position of motor.

2. Check voltage between G 13 (positive) and G 18 (negative). Display: approx. 5 volts.

Replace heater/air conditioner regulator if there is no voltage.

3. Pull off plug on drive motor.

4. Check pin 4 and pin 5 electric leads for breaks, short against ground and against battery voltage.

Test Point 9

Footwell flap motor 1. Check voltage between G 18 (negative) and G 27 (positive).

Points 2 through 4 - see Test Point 8.

Test Point 10

Fresh air flap motor 1. Check voltage between G 18 (negative) and G 20 (positive).

Points 2 through 4 - see Test Point 8.

Test Point 11

Left mixing flap motor 1. Check voltage between G 18 (negative) and G 25 (positive).

Points 2 through 4 - see Test Point 8.

Fault, Fault Code Possible Causes, Elimination, Remarks

Test Point 12

Right mixing flap motor 1. Check voltage between G 18 (negative) and G 8 (positive).

Fault Code 8 32 Display: 0.2 to 5 volts.

Points 2 through 4 - see Test Point 8.

Test Point 13

Left heater blower motor 1. Check whether final stage is screwed tight on the aluminum

Fault Code 8 _ 33 cooling panel.

2. Check whether motor is seized mechanically.

Test Point 14

Right heater blower motor See Test Point 13. Fault Code 8 34

1. Check voltage on terminals 30 and 30 C.

2. Check whether motor is seized mechanically; e.g. bridge terminals 30 and 87.

3. Check leads from relay to motor for breaks and ground shorts.

4. Check leads from motor to heater/air conditioner regulator G 7 for breaks.

Test Point 15

Condenser blower motor Fault Code 8 41

Test Point 16

Oil cooler blower motor Points 1 through 3 - see Test Point 15.

Fault Code 8 42 4- Check leads from motor to heater/air conditioner regulator G 9 for breaks.

Fault, Faun Code Possible Causes, Elimination, Remarks

Test Point 17

Rear blower motor speed 1 Points 1 through 3 - See Test Point 15.

Fault Code 8 43/46 4- Check electric leads from motor to heater/air conditioner regulator ~ G 19 for breaks.

5. Check electric leads from motor to relay term. 87 or to ballast resistor for short against battery voltage.

Test Point 18

Rear blower motor speed 2 Fault Code 8 44/47

1. Check voltage on terminals 30 and 30 C.

2. Check whether motor is seized mechanically, e.g. bridge terminals 30 and 87.

3. Check electric leads from relay term. 87 to motor for breaks and ground short.

4. Check electric leads from motor to heater/air conditioner regulator G 19 for breaks.

Test Point 19

Inside sensor blower motor Fault Code 8 _ 45

1. Check voltage on plug receptacle. Display: approx. 12 volts.

2. Check whether motor is seized mechanically.

Note on Test Item 17/18

The turbo is fitted with 2 rear blowers. Fault Codes 43 and 44 refer to the right-hand blower, 46 and 47 refer to the left-hand blower.

Since both the 911 Carrera 2/4 and the 911 turbo are fitted with the same heating/airconditioning blower, a separate jumper is fitted to the 911 Carrera 2/4 (also refer to page 87-27). For this reason, both fault codes, i.e. 43 and 46 or 44 and 47, respectively, are displayed at the same time whenever a fault in the rear blower is detected on the 911 Carrera 2/4.

Heating/air conditioning blower with index 01

H 03 - Heating regulator

H 04 - Heating and air conditioning regulator

Diagnosis was extended by additional features:

- Drive link activation

- Input signals

- Actual values

The following drive links can now be activated:

- Left mixing flap

- Right mixing flap

- Defroster flap

- Footwell flaps

- Fresh air flaps

- Rear blower

- Left heater blower

- Right heater blower

- Oil cooler blower

- Condenser blower (only H 04)

- Air-conditioning test (only H 04)

Operation of the drive motors for the flaps and the blower motor, respectively, is displayed via a bar graph (except for the heater blowers: in this case, operation is indicated by the operating noise). Incase of the drive motors, it is important for the bar graph display to change, i.e. the flaps must be operated from the open to closed and from the hot to cold positions, respectively, and vice versa.

In case of the air conditioning test, the evaporator temperature must drop below 5°C. If testing is not possible, check operation of the left and right mixing flaps and of the condenser blower.

The following input signals may be checked:

- Footwell flap

- Defroster flap

- Blower potentiometer

- Temperature potentiometer

- Air circulation switch

- Defroster switch

Operation of the potentiometers is displayed via a bar graph.

Modify position of potentiometers: the bar graph must increase or decrease, respectively.

Operation of the switches is indicated by the opened or closed position;

Switch not actuated: open Switch actuated: closed

The following actual values may be displayed:

- Voltage Term. X

- Inside temperature

- Rear temperature

- Mixing chamber temperature, left

- Mixing chamber temperature, right

- Oil temperature

- Evaporator temperature (only H 04)

Axial and Lateral Acceleration Sensors Location

The sensors are installed on a sheet metal console on the tunnel underneath the center console. These sensors are required for all wheel drive and antiblock systems.

1 - Lateral acceleration sensor

2 - Axial acceleration sensor

Sensor Pmh Porsche 964
290- 45

Installation

Always conform with the following points when installing:

1. Park car on level ground (level floor).

2. Check levelness of the sheet metal console with a bubble level. Replace a bent sheet metal console.

3. Connecting leads must not be mixed up. Plug receptacles have different colors for identification.

Black plug receptacle for the lateral acceleration sensor.

Gray plug receptacle for the axial acceleration sensor.

4. Sensors must not be subjected to any type of extreme acceleration such as from throwing, falling or knocking.

5. Sensors must always be inspected after an accident. Sensors must be replaced if they are not within specifications.

Checking

Checking is required to guarantee the following points.

- Correct location (position) of sensors

- Function of sensors

- Electric leads (plugs) connected on the correct sensor (mix-up test)

Testing is described in Rep. Gr. 45 (Volume IV - Chassis).

Checking fuel tank sender unit Visual inspection

1. The fuel tank sender unit must show no signs of mechanical damage.

2. The two flood holes on the bottom of the sender unit must not be obstructed.

Electrical operational check

1. Connect an ohmmeter to the unit connectors.

Note

The length of the measuring leads must not exceed 1 m.

2. Hold sender unit vertically, with the threaded flange pointing up:

3. Turn sender unit over; threaded flange points down. Reading: 1.1 Q to 2.5 Q

Note

Turn fuel tank sender unit over rapidly in one go.

The resistance read off immediately after the float has audibly bottomed out is the relevant measuring result.

4. Repeat test steps 2 and 3. Note

The values read off must remain within the limits for the entire duration of the test; if this is not the case, replace the sender unit.

Telephone preparation kits M 612 and M 195

C2-net telephone system (Philips) Cellular telephone system (USA only)

As from model 90, the 911 Carrera 2/4 can be equipped with a telephone preparation kit ex-works.

The preparation kit includes all necessary wiring harnesses, the holders for the radio device and the control units as well as the telephone antenna.

Note

Problems may occur during driving operation if the wiring harnesses are not routed as planned in the preparation kit or if telephone systems which are not approved by Porsche are installed in the case of subsequent installation.

Installation position of the components and cable routing in the vehicle

Diagnostic Porsche 964

A - Antenna Targa, Cabriolet 1 - Antenna cable, fender antenna

B - Central electrics 2 - Antenna cable to radio

C - Radio 3 - Supply cables

D - Control unit 4 - Cable, control unit

E - Transmitter/receiver unit 5 - Antenna cable, roof antenna F - Antenna duplexer G - Antenna, coupé

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

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