Headlamps Inoperative - Low Beams DRL Off
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Did the test lamp light? | -- | Go to Step 2 | Go to Step 3 |
2 | Backprobe the headlamp switch with a test lamp from terminal 4 to B+. Did the test lamp light? | -- | Go to Step 4 | Go to Step 5 |
3 | Repair the open in CKT 87 (BLK) between the headlamp switch and G105. Do the headlamps light? | -- | System OK | -- |
4 | Backprobe the lighting relay with a test lamp from terminal 86 to B+. Did the test lamp light? | -- | Go to Step 6 | Go to Step 7 |
5 | Replace the headlamp switch. Do the headlamps light? | -- | System OK | -- |
6 | Backprobe the lighting relay with a test lamp from terminal 85 to ground. Did the test lamp light? | -- | Go to Step 8 | Go to Step 9 |
7 | Repair the open in CKT 717 (RED/BLK) between the lighting relay and the headlamp switch. Do the headlamps light? | -- | System OK | -- |
8 | Backprobe the lighting relay with a test lamp from terminal 87 to B+. Did the test lamp light? | -- | Go to Step 10 | Go to Step 11 |
9 | Install a known good relay in place of the Lighting Relay. If headlamps still do not light, then repair the open in CKT 727 (ORN) between the IP fuse block and the lighting relay. Do the headlamps light? | -- | System OK | -- |
10 | Backprobe the lighting relay with a test lamp from terminal 30 to B+. Did the test lamp light? | -- | Go to Step 12 | Go to Step 13 |
11 | Backprobe the low/high lighting relay with a test lamp from terminal 30 to B+. Did the test lamp light? | -- | Go to Step 14 | Go to Step 15 |
12 | Repair the open in CKT 691 (RED/BLK) between S315 and the lighting relay. Do the headlamps light? | -- | System OK | -- |
13 | Replace the lighting relay. Do the headlamps light? | -- | System OK | -- |
14 | Backprobe the low/high lighting relay with a test lamp from terminal 86 to B+. Did the test lamp light? | -- | Go to Step 16 | Go to Step 17 |
15 | Repair the open in CKT 720 (BLK) between the low/high lighting relay and G105. Do the headlamps light? | -- | System OK | -- |
16 | Repair the open in CKT 721 (RED/YEL) between the low/high lighting relay, diode module 2, the instrument cluster, and the headlamp switch. Do the headlamps light? | -- | System OK | -- |
17 | Backprobe the low/high lighting relay with a test lamp from terminal 87A to B+. Did the test lamp light? | -- | Go to Step 18 | Go to Step 19 |
18 | Repair the open in CKT 716 (YEL) between the lighting relay and the low/high lighting relay. Do the headlamps light? | -- | System OK | -- |
19 | Replace the low/high lighting relay. Do the headlamps light? | -- | System OK | -- |
Headlamps Inoperative - Low Beams During DRL Operation
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Is the vehicle equipped with hydraulic brakes instead of air brakes? | -- | Go to Step 2 | Go to Step 8 |
2 | Backprobe the park brake switch with a test lamp from terminal 4 to B+. Does the test lamp light? | -- | Go to Step 4 | Go to Step 3 |
3 | Locate and repair the open in CKT 6 and CKT 27 (BLK) between the park brake switch and G105. Is the repair complete? | -- | System OK | -- |
4 |
Does the test lamp light? | -- | Go to Step 6 | Go to Step 5 |
5 | Replace the park brake switch. Is the repair complete? | -- | System OK | -- |
6 | Backprobe the DRL OFF 2 relay with a test lamp from terminal 86 to B+. Does the test lamp light? | -- | Go to Step 14 | Go to Step 7 |
7 | Locate and repair the open in CKT 5 and CKT 745 (BLU) between the DRL OFF 2 relay and the park brake switch. Is the repair complete? | -- | System OK | -- |
8 | Backprobe the park brake switch with a test lamp from terminal B to B+. Does the test lamp light? | -- | Go to Step 10 | Go to Step 9 |
9 | Locate and repair the open in CKT 746 (BLK) between the park brake switch and G105. Is the repair complete? | -- | System OK | -- |
10 |
Does the test lamp light? | -- | Go to Step 12 | Go to Step 11 |
11 | Replace the park brake switch. Is the repair complete? | -- | System OK | -- |
12 | Backprobe the DRL OFF relay with a test lamp from terminal 86 to B+. Does the test lamp light? | -- | Go to Step 14 | Go to Step 13 |
13 | Locate and repair the open in CKT 744 (LT BLU) between the DRL OFF relay and the park brake switch. Is the repair complete? | -- | System OK | -- |
14 |
Does the test lamp light? | -- | Go to Step 16 | Go to Step 15 |
15 | Locate and repair the open in CKT 749 (BRN) between the IP fuse block and the DRL OFF 2 relay. Is the repair complete? | -- | System OK | -- |
16 | Backprobe the DRL OFF relay with a test lamp from terminal 87 to B+. Does the test lamp light? | -- | Go to Step 18 | Go to Step 17 |
17 | Locate and repair the open in CKT 22 (BLK) between the DRL OFF relay and G105. Is the repair complete? | -- | System OK | -- |
18 | Backprobe the DRL OFF relay with a test lamp from terminal 30 to B+. Does the test lamp light? | -- | Go to Step 20 | Go to Step 19 |
19 | Replace the DRL OFF relay. Is the repair complete? | -- | System OK | -- |
20 | Backprobe the DRL ON relay with a test lamp from terminal 87A to B+. Does the test lamp light? | -- | Go to Step 22 | Go to Step 21 |
21 | Repair the open in CKT 741 (BLK/GRN) between the DRL ON relay and the DRL OFF relay. Is the repair complete? | -- | System OK | -- |
22 |
Does the test lamp light? | -- | Go to Step 23 | Go to Step 26 |
23 | Check for a short to ground in CKT 740 (BRN) between the DRL ON relay and the generator. Is the circuit in need of repair? | -- | Go to Step 24 | Go to Step 25 |
24 | Repair the short to ground in CKT 740 (BRN) between the DRL ON relay and the generator. Is the repair complete? | -- | System OK | -- |
25 | Refer to Engine Electrical in order to diagnose the charging/generator system. Perform repairs as necessary. Is the repair complete? | -- | System OK | -- |
26 |
Does the test lamp light? | -- | Go to Step 28 | Go to Step 27 |
27 | Locate and repair the open in CKT 739 (BRN) between the IP fuse block and the DRL ON relay. Is the repair complete? | -- | System OK | -- |
28 | Backprobe the DRL ON relay with a test lamp from terminal 30 to B+. Does the test lamp light? | -- | Go to Step 30 | Go to Step 29 |
29 | Replace the DRL ON relay. Is the repair complete? | -- | System OK | -- |
30 | Backprobe the DRL series dropping resistor with a test lamp from terminal A to B+. Does the test lamp light? | -- | Go to Step 32 | Go to Step 31 |
31 | Locate and repair the open in CKT 729 (RED/BLK) between the DRL series dropping resistor and the DRL ON relay. Is the repair complete? | -- | System OK | -- |
32 |
Do the low beam filaments light? | -- | Go to Step 33 | Go to Step 34 |
33 | Replace the DRL series dropping resistor. Is the repair complete? | -- | System OK | -- |
34 | Do not disconnect the jumper. Backprobe the lighting relay with a test lamp from terminal 87A to B+. Does the test lamp light? | -- | Go to Step 36 | Go to Step 35 |
35 | Locate and repair the open in CKT 715 (RED/YEL) between the lighting relay and the DRL series dropping resistor. Is the repair complete? | -- | System OK | -- |
36 | Replace the lighting relay. Is the repair complete? | -- | System OK | -- |
