A: No Communication With GEM

PINPOINT TEST A: NO COMMUNICATION WITH GENERIC ELECTRONIC MODULE (GEM)

A1 - CHECK CIRCUIT 785 (BK/LG) FOR POWER

Disconnect generic electronic module (GEM) connector C1.

Using a voltmeter, measure for voltage at GEM connector Pin C1-13, Circuit 785 (BK/LG).

Is voltage B+?

YES GO to A5.

NO GO to A2.

A2 - CHECK CIRCUIT 785 (BK/LG) FOR SHORT TO GROUND

Remove Fuse 19 (1OA) from fuse junction panel.

Using an ohmmeter connected to ground, measure resistance at GEM connector Pin C1-13, Circuit 785 (BK/LG).

Is resistance less than 10K ohms?

YES SERVICE Circuit 785 (BK/LG) for short to ground. REPLACE Fuse 19 (10A). RESTORE vehicle. RETEST system.

NO GO to A3.

A3 - CHECK SUPPLY TO FUSE 19 (10A)

Remove Fuse 19 (1OA) from fuse junction panel.

Using a voltmeter, measure for voltage at Fuse 19 input cavity.

Is voltage B+?

YES GO to A4.

NO SERVICE supply to Fuse 19 (10A). RESTORE vehicle. RETEST system.

A4 - CHECK CIRCUIT 785 (BK/LG) FOR OPEN

Using an ohmmeter, measure resistance of Circuit 785 (BK/LG) between GEM connector Pin C1-13 and output cavity of Fuse 19.

Is resistance 5 ohms or less?

YES REPLACE Fuse 19 (10A). RESTORE vehicle. RETEST system.

NO SERVICE Circuit 785 (BK/LG) for open. RESTORE vehicle. RETEST system.

A5 - CHECK CIRCUIT 489 (PK/BK) FOR POWER

Disconnect generic electronic module (GEM) connector C2.

Using a voltmeter, measure for voltage at GEM connector Pin C2-22 Circuit 489 (PK/BK).

Is voltage B+?

YES GO to A9.

NO GO to A6.

A6 - CHECK CIRCUIT 489 (PK/BK) FOR SHORT TO GROUND

Remove Fuse 21 (10A) from fuse junction panel.

Using an ohmmeter connected to ground, measure resistance at GEM connector Pin C2-22, Circuit 489 (PK/BK).

Is resistance less than 10K ohms?

YES SERVICE Circuit 489 (PK/BK) for short to ground. REPLACE Fuse 21 (10A). RESTORE vehicle. RETEST system.

NO GO to A7.

A7 - CHECK SUPPLY TO FUSE 21 (10A)

Remove Fuse 21 (10A) from fuse junction panel.

Using a voltmeter, measure for voltage at Fuse 21 input cavity.

Is voltage B+?

YES GO to A8.

NO SERVICE supply to Fuse 21 (10A). RESTORE vehicle. RETEST system.

A8 - CHECK CIRCUIT 489 (PK/BK) FOR OPEN

Using an ohmmeter, measure resistance of Circuit 489 (PK/BK) between GEM connector Pin C2-22 and output cavity of Fuse 21.

Is resistance 5 ohms or less?

YES REPLACE Fuse 21 (10A). RESTORE vehicle. RETEST system.

NO SERVICE Circuit 489 (PK/BK) for open. RESTORE vehicle. RETEST system.

A9 - CHECK CIRCUIT 397 (BK/W) FOR OPEN

Using an ohmmeter connected to ground, measure resistance at GEM connector Pins C1-25, C1-26 and C2-15.

Is resistance less than 5 ohms?

YES Diagnose network concern.

NO SERVICE suspect Circuit 397 (BK/W) for open. RESTORE vehicle. RETEST system.