Wiring question...

[rnettleship]

I noticed that the previous owner of my 98 Navigator ran two wires to the rear of the vehicle.

1) Charcoal canister vent solenoid
2) Rear air suspension ride height sensor.

When testing the original wires for the ride height sensor I had less than 1 volt going to the sensor when it should have been 4.8v. The PO just tapped off the front height sensor.

My question is... Are there any known issues with the wiring harness on these vehicles? I can see having an open circuit if something was damaged but a little hard to understand very low voltage.

Also, I have not tested the vent solenoid yet but I do have a P0455 code which could possibly be the solenoid stuck open.

Any comments are welcome.

 

[stamp11127]

No issues that I know of. As resistance increases, voltage and current decrease. Since your in a salt state I would say corrosion is a common way of life.

P0425 - This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected.

Read more at: OBD-II Trouble Code: P0455 Evaporative Emission Control System Leak Detected (no purge flow or large leak)
Copyright © OBD-Codes.com

 

[rnettleship]

Thanks. I just ordered the Ford shop software so I'll wait until that comes to dig deeper. I doubt there is a connector under the vehicle between the back of the car and the fuse box or whatever module controls these items but you never know. It should be easier to trace when I get the wiring diagrams.

My suspension light comes on a short time after starting the car but it seems to work fine. If anything it looks like it might be too high so I'm thinking that even though the ride height sensor is working, there may be a problem getting the correct voltage back to the module that makes it all work. If the wire that supplies the voltage isn't good than maybe the return isn't as well.

 

[stamp11127]

The 2000 model shows 2 connectors in the harness between the ride height control and the module by the steering column.

 

[rnettleship]

Great. Thanks for the info. I'm going to attempt to read the voltage for the ride height sensors at the 4WAS box to test my theory. Looks like that won't be easy given it's location. I read somewhere that if the check susp light comes on within 45 seconds the system is having trouble venting and if it comes on in 90 seconds it is having trouble inflating to correct height. I never hear the pump run for more than 30 seconds so I'm guessing it just might be a stuck vent solenoid.

Lot's of guessing at the moment but at least I don't have a "squatter"

 

[rnettleship]

One other question... What do I need to read the suspension error codes or for that matter any of the codes other than the CEL related? I have the simple ODBII bluetooth adapter and Android phone app but I assume I can't access these kinds of codes through that method. Not looking to spend a fortune. For my Mercedes I bought a multiplexer, cables and questionable software off EBay that gives me access to everything for about $75.

 

[stamp11127]

Send me your email with what year Expy are we talking about. I would guess that you will need a high dollar scan tool to read the dtc's for the suspension. The codes start with B or C. Most members do the conversion to springs.

 

[rnettleship]

Update - Seems like the compressor relay and ride height sensors are fine. I think the problems is that the system is not able to release air pressure fast enough. I tow a 5k # trailer and each time I hook it up the compressor starts and the rear end rises to compensate. When I unhook the trailer, the ride height stays the same and does not lower appreciably. Yesterday the entire car was pretty high in the air and I turned the key on and could hear a faint hissing at the compressor. This lasted about a minute and stopped. The vehicle was still high. I opened the door and closed it and the hissing started again and stopped after a minute. Repeating this about 5 times and vehicle seemed to have lowered to the correct height. The hissing on the last attempt only lasted about 10 seconds so I believe the system finally achieved it's expected height and turned off. When I started the car the compressor turned on for a few seconds.

This all leads me to believe the electronics are ok but possibly a blockage in the system not allowing air to escape fast enough and the system closes the solenoids after a timeout. I was thinking it could be the drier on the after market (Arnott) compressor needs replacing. Cheap enough to try but I don't know how to release the pressure in the system to make the swap.

Any suggestions? And yes, I am aware of the coil replacement systems. For now I would like to figure this out and keep the air ride.

 

[stamp11127]

crack a line fitting - very carefully of course

 

[fourty03]

If you have a Bluetooth capable laptop, you could try Forscan, which I is free and would read the suspension codes.

For android, you could use OBD Car Guage Pro to connect to the suspension module to read it as well.

Sent from my Prism II using Tapatalk 2

 

[rnettleship]

Thanks, I'll try both of those and see what I get.

 

[rnettleship]

Fourty03---Thanks for the tip on the FORSCAN. I thought I needed a big $ scanner to access those codes. I ran the self tests and came back with a C1770 Air Suspension Control Module Air Suspension Vent Solenoid Output Circuit Failure. This lines up with my theory that the system is having difficulty venting to lower the vehicle. Tonight I will check to see if I have 12v going to the vent solenoid on the compressor and if so, make sure I don't have any issue with an exposed wire arcing to ground. If that all pans out I guess I will need to contact Arnott for either a new solenoid or compressor unit. (Hoping to avoid that expense)

 

[rnettleship]

Thanks for the tip on Forscan. It works great. I pulled the compressor and found the two leads going to the vent solenoid had their insulation worn through in a few spots. I put some shrink tubing on them and attached to a battery. I could hear the solenoid work and verified that when it did I could blow air through the compressor. I pulled the drier as well and blew air through that. It did have some resistance but I don't know how much is "normal".

In my haste to see if my work was successful I forgot to hookup the two air lines so when I started the car the rear end completely deflated It took the pump about three full cycles to get the rear end back up and the ride height sensors seem to be working fine. I ran the 4AWS self test several times and I no longer have the C1770 code. For now I will claim victory but I did not have the opportunity to drive it around so time will tell.

On another note, I still have the jumper wire going to my rear sensor which I really don't like. The wiring diagram shows a connector under the hood but I can't find it. Based on the picture I assume it is referring to the primary harness connector that bolts to the firewall, under the brake booster. No sure I want to mess with that one.

 

[Bedrck47]

rnettleship

kindly update your signature in the USER CP section with your expy information. As this will help to provide you with better information specific to your expy

 

[rnettleship]

Case closed. I drove the vehicle over 100 miles last night, half towing a trailer and half not. Everything is working fine now. Looks like wires going to the vent solenoid was the culprit.

 

[Bedrck47]

thanks for the update

I wish more members would take the time to give updates on the results to let those that offer help know.