No Response (Help 1)

Note: The following example was written for a DRB II. Procedures for other scan tools will vary. Follow manufacturer's instructions for the scan tool being used.

Warning: Apply parking brake and/or block wheels before performing any test on an operating engine.

1. Connect the scan tool to the diagnostic connector located in the engine compartment. The separate red clip is connected to the positive post of the battery.

2. With the scan tool properly connected, all character positions on the display should briefly illuminate, and the copyright message should appear.

- If the screen is blank after the scanner is attached to the vehicle, SEE Blank Screen Troubleshooting below.

- If the screen shows ``NO RESPONSE'', SEE No Response Troubleshooting below.

Blank Screen Troubleshooting

Note: If the screen is blank after the scan tool is attached to the vehicle:

a. Make sure all cable connections are properly seated and fit snugly.

b. Make sure the cables are in good condition (no broken or shorted wires).

c. Make sure the cartridge is installed properly into the scan tool.

d. Try the scan tool on another vehicle.

- If it now performs properly, continue with next step.

- If the scan tool screen is still blank, have the unit repaired.

Data Link Connector Identification:

e. Make sure all cable connectors are in good condition (no flared or pushed out terminals). If the connector is good, continue with next step.

On-Board Diagnostic Connector Identification (Wire Color May Vary By Model):

f. Check the BK/* wire in the diagnostic connector (terminal 1) for continuity to ground

No Response Troubleshooting

Note: Checking the following items, in order, will uncover the reason for the ``No Response'' message. Read the following conditions that are required to receive a response on the DRB II and perform the appropriate repairs for the conditions that are not met.

a. The ignition key must be on.

b. The PK wire between engine controller cavity 25 and the diagnostic connector must not be shorted to ground. Also, the PK wire must have continuity between the engine controller and the diagnostic connector.

c. The LG wire between engine controller cavity 45 and the diagnostic connector must not be shorted to ground. Also, the LG wire must have continuity between the engine controller and the diagnostic connector.

d. The DRB II, DRB II cartridge, and the DRB II adapter cable must be functional. This may be determined by method of substitution (trying sequentially another vehicle, cable, cartridge, and DRB II).

e. If the above listed items are OK, replace the engine controller. NOTE: Trucks must have the EMR mileage set and vehicles equipped with a factory theft alarm must be started twenty times to enable the theft alarm.