Td Signal Test

Fig. 16 Idle Speed Control Unit Plug Terminal ID:

1. Remove idle speed control unit. Run engine at idle speed (idle rpm = 660 ±40). Select VOLTS AC on multimeter and check voltage between sockets 10 and 11 of idle speed control unit plug, Fig. 16. If a voltage signal of greater than 2.8 volts AC is obtained, then the unit is good, test is over. If a voltage signal of greater than 2.8 volts AC is not obtained, proceed to step 2.

Fig. 18 Idle Speed Control Unit and A/C Control Unit Plug Terminal ID:

2. Shut off engine and remove A/C compressor control unit. Select Ohm on multimeter and check wire between socket 10 of idle speed control unit plug and socket 3 of A/C compressor control unit plug for continuity, Fig. 18. If the ohmeter reading is less than 1 Ohm, proceed to step 3. If the ohmeter reading is more than 1 Ohm, repair the open circuit.

Fig. 59 A/C Compressor Control Unit Plug:

3. Check the resistance between sockets 1 and 2 of A/C compressor control unit plug, Fig. 59. If reading is 1.9 ±0.2 kOhm, then proceed to step 4. If reading is not 1.9 ±0.2 kOhm, then check wires according to wiring diagram. If wires are ok, replace ring gear speed sensor.
4. Select VOLTS AC on multimeter. Run engine at idle speed (660 ±40 rpm) and check voltage between sockets 1 and 2 of A/C compressor control unit plug. If reading is greater than 4 volts AC and increases with increasing rpm, proceed to step 5. If not, check ring gear speed sensor for dirt accumulation, cleaning or replacing as necessary.
5. Shut off engine and select position "2" on preglow/starter switch. Select VOLTS DC on the multimeter. Check voltage between sockets 1 (-) and 5 (+) on A/C compressor control unit plug, Fig. 59. If voltage reading is approximately 12 volts, replace the A/C compressor control unit. If the voltage reading is not approximately 12 volts check for and repair open circuit.