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84-89 Cluster Bench Testing

Before we located factory connectors, we made our own test harness, using stuff available at my local Radio Shack. The connector I used is RS part number 276-1430, a DB25 Female CRIMP (not solder) connector. You'll need six of these connected to +12V, and three of these connected to ground.

 

Update: You can now purchase a bench test power cable with factory connectors Click here

 

Note: If you purchased the bench cable with factory connectors installed, Click here for documentation.

 

Female DB25 Crimp connectors used to connect to the cluster pins

 

A crimp connector, soldered to 22ga wire.

 

Heat Shrink Applied to the crimp connector

 

Complete Test Harness

 

Testing the Cluster

Wiring Diagrams and Cluster Pinout - Click Here

 

  1. You'll need a 12VDC power supply capable of supplying at least 5 Amps. A small lead acid battery or bench power supply is fine.

  2. Connect the positive terminals (red wires) to pins C16, D5 and D16. See the jumper leads above. If you purchased the bench test cable from us, the red wires are connected to +12V.

  3. Connect the negative terminal (black wires) of the power supply to pins B1 and D1 and D3. If you purchased the bench test cable from us, the black wires are connected to ground. Leave these two leads in place for the duration of the testing.

  4. Power on the power supply. The four backlights should illuminate brightly, and all segments all three LCDs should turn on for a few seconds. Note that a few segments are not meant to light up, such as those in the upper left of the leftmost seven segment displays in the speedometer and center panel.

  5. After a few seconds, the lamps should remain brightly illuminated, and all segments should go out except: The MPH and Tach should show "0".

  6. Covering the photocell (to simulate dark operating conditions) should cause the cluster to dim, and shining a light on the photocell (or allowing room light to reach it) should cause it to go to full brightness.

  7. Covering and uncovering the photocell should cause the cluster brightness to change, whether the headlights are on or off.

  8. Connect a red wire to pin C2 and the left turn indicator should light. Remove the red wire from pin C2.

  9. Connect a red wire to pin C3 and the high beam indicator should light. Remove the red wire from pin C3.

  10. Connect a red wire to pin C4 and the right turn indicator should light. Remove the red wire from pin C4.

  11. Connect a black wire pin A9 to show Oil Pressure on the center panel. Connect a black lead to pin C1. The oil pressure should change from from low to high. Remove the black leads from pin C1 and A9.

  12. Connect pin A10 to ground to show Oil Temp on the center panel. Connect a black lead to pin D6. The oil temperature should vary from low to high. Remove the black wire from pins D6 and A10.

  13. Connect a black wire to pin A8 to show battery voltage on the center panel. The voltage should read the same as the battery measures, or should be +12V if you're using our bench test cable. Remove the black wire from pin A8.

  14. Connect a black wire to pin A10 to show Coolant temp on center panel. Connect a black lead to Pin D4. The coolant temp should change from 'LO' to high. Remove the black wire from pins D4 and A10.

  15. Connect pin A4 to ground briefly to reset the trip odometer.

  16. Connect a black lead to pin C8. The fuel level graph should slowly change from full to empty. Remove the black lead from pin C8.

  17. To test the tachometer, you'll need a signal generator (or a simple 555 timer circuit). Set it to square wave or sine wave, 1Vpk (2Vpk-pk) amplitude, and 30Hz. Connect the (+) output of the signal generator to C5, and the (-) terminal to the GND terminal of the battery. This should cause the tachometer to show 500RPM. Increase frequency to 400Hz, when the cluster should show 6000RPM. Don't increase beyond 400Hz.

  18. Testing the speedometer: Warning: This step will cause the odometer to increase. It's a good way to test the odometer, but if you don't want to do that, disconnect the odometer wire before performing this test. You'll need a signal generator (or a simple 555 timer circuit). Set it to square wave or sine wave, 1Vpeak (2Vpk-pk) amplitude, and 20Hz. Connect the (-) terminal of the sig gen to the C15 terminal of the cluster, and the (+) terminal to the D11 terminal of the cluster. The speedometer should show 18MPH. Increase the frequency to 200Hz, when the speedometer should show approximately 178MPH. Don't increase the frequency beyond 200Hz.