Instruments - Testing
86porsche01Subject:
Testing of Instruments
Model
944/944T
Group
9
Part Identifier
N/A
Number
8604
October 24, 1986
Testing of Instruments 944/944 Turbo Model Year 1985/2 - 86
VW tool 1301 can be used to check field values. However, 1301 must be adjusted to test value using an ohm meter. If 1301 or equivalent is not available, resistors of corresponding values can be used.
Temperature Gauge Range Testing
Test connections: 14 pole connector in engine compartment near brake booster.
Connect resistance between term 8 and chassis ground. Gauge should read:
Range 1 - 287 ohms Range 3 - 38 ohms
Oil Pressure Gauge Indication Test Connections:
14 pole connector in engine compartment.
Connect resistance between terminal 6 and chassis ground. Gauge should read:
1 - Bar - 30 ohms 5 - Bar - 184 ohms
Fuel Gauge Range Checking Test
Connections: At rear on sending unit plug.
Connect resistance between terminal 1 and
3. Gauge should read:
1/4 tank - 42 ohms Full tank - 3 ohms
Voltmeter Indication - Testing for battery voltage.
Locate connector "C" of instrument assembly. Connect voltage tester to pin 5 (term. 15) and to pin 8 (term. 31). Tester should display battery voltage with ignition on.
Speedometer
Checking voltage supply and ground at connectors "B" and "A" of instrument cluster. Connect tester to pin 13 of connector "B" (term. 15) and pin 9 of connector "A" (term. 31). With ignition switch on, battery voltage should be displayed.
Speed Transmitter Input to Speedometer Checking:
Test Connections: Connector "B" pin 14 of instrument cluster (input). Same connector, pin 15 (output).
Signal from transmitter through speedometer can be tested at lifting roof relay terminal I for "85" models and terminal A for "86" models. Signal can also be tested at cruise control unit plug 1 terminal 1. For this test rear wheels must be turning. Using oscilloscope, angular pattern should be displayed.
Tachometer Voltage Supply, Ground, and RPM Signal Checking
With ignition on, check for battery voltage at instrument cluster connector "B" pin 4 (term. 15) and pin 2 (term. 31).
RPM Signal Checking: Connect oscilloscope lead to instrument cluster connector "B" pin 3 (input to tach). Angular pattern should be displayed with engine idling.
Upshift Indicator Checking
Three inputs are required for proper upshift indicator operation.
1) Speedometer Signal Checking:
Lifting roof relay or connector "B" pin 15 of instrument cluster. Using oscilloscope, angular pattern should be displayed with drive wheels moving.
2) Fuel Injection Signal Checking:
Connect oscilloscope test lead to pin 1 of 4 pin connector behind glove compartment. Fuel injection signal can also be tested at instrument cluster connector "B" pin 5. An angular pattern should be displayed at engine idle.
3) Coolant Temperature Signal Checking:
Connect ohmmeter to instrument cluster connector "A" pin 3 At 60 degrees C approx. 140 ohms 90 degrees C approx. 50 ohms 100 degrees C approx. 38 ohms
60 degrees C = 140 degrees F 90 degrees C = 194 degrees F 100 degrees C = 212 degrees F
Consumption Meter Input Checking
1) Using oscilloscope, check speedometer transmitter signal at instrument cluster connector "B" pin 15. Connector must be plugged to instrument assembly. An angular pattern should be displayed with rear wheels moving.
2) Fuel injection signal:
Connect oscilloscope test lead to instrument cluster connector "B" pin 5 or at 4 pin connector behind glove compartment, terminal 1. With engine idling, an angular pattern should be displayed.