eohalloran
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- Jul 7, 2011
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The rear end on my 1999 Expedition has gone down for the second time in 2 years. Last time I had this fixed it cost me $1300, so I want to be able to do some basic testing and resolution myself.
First thing I noted after the rear end had gone down was that the hose going to the driver's side rear suspension air bag had snapped off and was dangling. I cut this back to pliable rubber and re-attached it. I suspect that when this came off the compressor was working overtime and either it or the relay blew.
When I switch on the ignition I do not hear the compressor running. Also, just as an idiot test, I detached the hoses to feel for any air, but got nothing so assume that it is most definitely not running.
I have checked the fuses and they are ok. I have also checked the 50A relay and that is OK and proved it further by swapping with another one in the box.
I have located both the compressor relay and the compressor /drier. But I need to now know how to test these. From my searches online I discovered that the control box is supposed to send a ground to the relay to activate it, but I don't know which of the 4 pins this is supposed to be applied to.
I also get a reading of about 10.6 volts on the red wire to the compressor regardless of if the ignition is on or off so I suspect that the relay passes a ground to the compressor to complete the circuit??? The compressor has 4 wires, red and black, and blue and white. The relay has 4 connections labelled A, B, C and D
Could anyone provide a wiring diagram or instructions on how to test these???
I did search this forum but did not find any similar requests.
Thanks
First thing I noted after the rear end had gone down was that the hose going to the driver's side rear suspension air bag had snapped off and was dangling. I cut this back to pliable rubber and re-attached it. I suspect that when this came off the compressor was working overtime and either it or the relay blew.
When I switch on the ignition I do not hear the compressor running. Also, just as an idiot test, I detached the hoses to feel for any air, but got nothing so assume that it is most definitely not running.
I have checked the fuses and they are ok. I have also checked the 50A relay and that is OK and proved it further by swapping with another one in the box.
I have located both the compressor relay and the compressor /drier. But I need to now know how to test these. From my searches online I discovered that the control box is supposed to send a ground to the relay to activate it, but I don't know which of the 4 pins this is supposed to be applied to.
I also get a reading of about 10.6 volts on the red wire to the compressor regardless of if the ignition is on or off so I suspect that the relay passes a ground to the compressor to complete the circuit??? The compressor has 4 wires, red and black, and blue and white. The relay has 4 connections labelled A, B, C and D
Could anyone provide a wiring diagram or instructions on how to test these???
I did search this forum but did not find any similar requests.
Thanks