8206noco.fm Page 194 Thursday, July 2, 1998 1:19 PM
SYMPTOM RELATED DIAGNOSTICS ENGINE BRAKE VERBAL COMPLAINT (continued) Test 40 Checking for an open or short in the harness 1. Reconnect the engine harness to the brake electrical studs on the engine. 2. Measure the resistance from pin A, on the harness side of the pressure switch connector between the switch and the solenoids, to a good ground.
If the resistance is within the range specified below, proceed to Test 80. If the resistance is not in this range, there is an open or short to ground in the harness between the pressure switch and the cylinder head stud. Locate and repair the open or short.
1. With the ignition key in the ON position, measure the voltage on one relay between pin 87 on the relay connector and a good ground.
If there is voltage on pin 87, locate and repair the short to voltage on the wire leading to pin 87 between the relay connector and the engine. Retest to be sure the problem has been corrected. If there is no voltage, repeat the procedure for each engine brake relay. If all of the relay test results lead to this step, proceed to Test 128.
Test 80 Checking for an open between the bulkhead connector and the engine or pressure switch
Resistance Ranges (in Ohms) E7 Dynatard
E9 Dynatard
Jacobs Dual Relay
Jacobs Single Relay
4–6
2–3
9.7–14.3
4.8–7.2
Test 64 Checking for voltage from other lines
1. Disconnect the bulkhead connector which contains the wire(s) that drive the engine brake solenoid (see schematic that came with the truck). 2. Measure the resistance from each engine brake bulkhead pin (one at a time) to a good ground.
If the resistance is within the range specified in the table below, there is an open or short between the bulkhead connector and the engine brake relay connector(s). Locate and repair the open or short. Retest to be sure the problem has been corrected. If the resistance is not within the specified range, there is an open or short between the bulkhead connector and the engine brake solenoids, or if a pressure switch is used, between the bulkhead and the pressure switch. Locate and repair the open or short. Retest to be sure the problem has been corrected. Resistance Ranges (in Ohms)
Figure 314 — Voltage from Pin 87 to Ground
Page 194
E7 Dynatard
E9 Dynatard
Jacobs Dual Relay
Jacobs Single Relay
4–6
2–3
9.7–14.3
4.8–7.2
