407910-1310 ZEXEL CONTROL UNIT Cross 4079101310

1. Disconnect plug P7 from receptacle J7. Check the connections for damaged wires or pins and corrosion. Also check that the pins are at the proper height in the connector. Check that the wires and pins are tight in the connectors by pulling (slightly) on each wire of each connector (including the breakout "T").2. Install the 9X1160 Adapter (forty pin breakout "T") between J7 and P7 and secure the connections.3. Connect the voltmeter as shown. Check for the appropriate voltages between the lettered "T" pins as explained in Steps 4 through 18.4. Check system voltage.Pin 1 (+) to pin 2 (ground) system voltage should be approximately 12 volts DC with key on (no accessories). Minimum voltage is 11.0 volts DC. While cranking the voltage should be 8 to 12 volts DC. Diagnosis - Using the truck wiring schematic, check wires 1 and 2 and connections from J7 through the truck wiring harness back to the battery terminals for proper voltage.5. Check voltage drop from battery.If the voltage check between pins 1 and 2 on P7 is less than 11.0 volts with the key on, check the voltage drop from pin 2 of the J7 connector to the negative battery post while cranking. For this test, the common lead (black) should be connected to the negative battery post first. Then place the positive (red) lead into pin 2. (Pin 2 is chassis ground). Voltage should be less than .5 volts DC when cranking. Diagnosis - If voltage drop is greater than .5 volts DC, check wire 2 and connections (including the battery post connections) from J7 to battery negative.6. Parking BrakePin 11 (parking brake) to 2 (ground):* Less than .5 volts DC with the key on and parking brake applied.* More than 4.5 volts DC with the key on and parking brake released. Diagnosis - Disconnect breakout "T" and check the individual switch circuits for open, ground or faulty switch. Switch circuit must have less than 10 ohms resistance and more than 20,000 ohms resistance to chassis ground.7. Check brake switch.Pin 30 (brake switch) to 2:* Less than .5 volts DC with the key on.* More than 4.5 volts DC with brake pedal applied and the key on. Diagnosis - Disconnect breakout "T" and check the individual switch circuits for open, ground or faulty switch. Switch circuit must have less than 2.5 ohms resistance and more than 5000 ohms resistance to chassis ground.8. Check vehicle speed buffer.When testing for speedometer problems on trucks that have a single sensor with a single winding for vehicle speed, also follow J14 tests 6, 7 and 8.A. Disconnect the two buffer input wires from the Vehicle Speed Sensor. Using a long jumper wire, connect the white input wire to P7 Pin 1 (+ battery).* With key ON, engine OFF, measure voltage from P7 Pin 33 (vehicle speed) and P7