Measurements Required for Troubleshooting. -726250112

TM 9-2320-364-34-1

2-8. TROUBLESHOOTING INSTRUCTIONS (CONT).

(28)

Retard command. When the retard control is operated (see Step [27] Retard request) the ATEC ECU

gives a command to operate the engine brake. The readout indicates YES when the retard command is

given and NO when the command is not given.

(29)

Special input. This readout indicates the position of a special input switch used for certain options, ON or

OFF.

(30)

Range commanded. This is the output signal to indicate that a specific gear range has been attained. The

readout is YES or NO.

(31)

Input voltage. The readout indicates the voltage available to the ATEC ECU.

Measurements Required for Troubleshooting.

Use proper sized test leads and ensure care is used when checking for resistance, continuity or

voltage at connectors or damage to equipment can result.

(1)

Resistance measurements.

(a)

Connect red test lead to Volt-Ohm input connector and black lead to COM input connector

on meter.

(b)

Set the function/range switch to the desired ohm position. If the magnitude of the resistance is not

known, set the switch to the highest range, then reduce until a satisfactory reading is obtained.

(c)

If the resistance being measured is connected to a circuit, turn ENGINE switch OFF.

(d)

Connect test leads to the circuit being measured. When measuring high resistance, be careful not to

contact adjacent points, even if they are insulated. Some insulators have a relatively low insulation

resistance which can affect the resulting measurement.

(e)

Read the resistance value on the digital display.

(2)

Continuity checks.

(a)

Place the function/range switch in any ohm range.

NOTE

Some meters show "1+m", or simply "1" when function/range switch is in any ohm

position.

(b)

Connect the red test lead to the Volt-Ohm input connector and black lead to COM input connector

on the meter. When the test leads are separated or measuring an out-of-range resistance, the digital

display will indicate "OL'' (Over Limit).

(c)

Put one test probe at one end of the wire or circuit to be tested. Use the other test lead to trace the

circuit. When continuity is established, an ohm symbol will appear in the upper left corner of the

digital display. If contact in the wire is maintained long enough (about of a second), the OL will

disappear and the resistance value of the wire or circuit will appear next to the symbol.

(d)

If your multimeter does not work in this manner, learn how it operates before performing

troubleshooting.

2-30