Front end noise
#12
Do you have vacuum on one of the lines at the vacuum switch on the firewall? Should show manifold vacuum at all times when the engine is running.
Edit: At the vacuum switch on the firewall there are two wires: a brown wire and grey with a black trace wire. Does the brown wire show battery voltage when the ignition is in the RUN position?
Edit: At the vacuum switch on the firewall there are two wires: a brown wire and grey with a black trace wire. Does the brown wire show battery voltage when the ignition is in the RUN position?
Last edited by Captain Hook; 02-05-2013 at 08:11 PM.
#15
If the actuator under the battery does not get vacuum when you select 4WD, the axle will not engage. The vacuum switch on the firewall is activated by the TCCM when you select 4WD. The vacuum switch is continuously supplied vacuum from the engine when the engine is running. The switch applies vacuum to the actuator. The actuator pulls the cable to operate the clutch. When the axle engages, it activates a switch on the axle tube that tells the TCCM that the axle is engaged. If it does not activate the switch on the axle tube, the TCCM will deactivate the vacuum switch and the lights will blink, telling you the axle is not engaged and 4WD is inoperative. The transfer case will remain in HI range though. You'll need a volt meter to check for voltage at the vacuum switch on the firewall.
#19
Range set on "VDC 20". Red probe in red hole bottom right. Black probe in center hole on the bottom.
Disconnect the electrical connector from the vacuum switch. Ignition in RUN position. Hold the black test probe on the battery negative terminal. Touch the red probe to the brown wire terminal in the harness connector. Read voltage.
Disconnect the electrical connector from the vacuum switch. Ignition in RUN position. Hold the black test probe on the battery negative terminal. Touch the red probe to the brown wire terminal in the harness connector. Read voltage.