Check Air Suspension Diagnostic Help please

[Barney366]

I have a 1996 Mark VIII, 87000 miles, air suspension is all original. The car spent most of its life in Maryland and Delaware, the past three in Mass but she's seen very few miles up here until I picked her up in April.

I could use some help diagnosing the Check Air Suspension warning I'm getting. Here's what's happening:

The rear suspension seems fine, always at a near constant height.

The front suspension seems to hold the height for 2-3 days. If she's been sitting for longer the suspension generally bottoms out. She inflates fine when I first start her, and the front raises up maybe 2-3 inches over the tire, even if the suspension had been bottomed out. The suspension warning will come on when I've been driving on the highway, could be anywhere from 5-20 minutes into the ride, although sometimes it doesn't occur. When I get to my destination (usually work) I notice that the suspension has fully bottomed out. I have pulled over a few times, shut the car off for a few minutes, then turned her back on and the car will raise to the proper height. Sometimes the warning comes on, sometimes not. When the warning does NOT come on the suspension height at arrrival seems fine (2-3" above the wheel).

Leaving after work, after sitting for 8 hours, the suspension will properly raise but the warning will most likely come on again.

So the airbags seem OK, maybe the compressor, solenoid valves, controller? Any insight would be appreciated, thanks in advance.

Maybe I'll bail on the air suspension and go with the spring conversion...

 

[Barney366]

One more piece of information: the warning does not seem to occur if I'm driving around town, speed limited to less than 45mph.

 

[billcu]

My green 94 had intermittent compressor problems like that too. I replaced the compressor relay and it seems to be ok now, I need to drive it more to be sure.

I had a spare, but you can use the one from the ABS pump in the driver's side fender to test it out.

 

[Barney366]

Thanks billcu!!

Unfortunately I can't swap the ABS relay in, as this only occurs when driving highway speeds, I'd rather not mess with the ABS / brakes.

I'll try pulling the relay and checking / cleaning the contacts first. If the problem persists I'll have to try replacing it. The part number is f3lb 2c013 aa. There's a bunch on eBay, used, in the $20-$30 range but I'm leery of those. Going to try and dig up some NOS.

 

[billcu]

You have a 96, so you have another spare relay to try, the secondary air injection pump uses one of those relay's too.

I'd hate to see you buy one if that's not the problem.

 

[93mark8rules]

Does the check Air Ride Message only come on over 60? Also if you drive around town long enough does it drop? Is it just the front suspension that drops?

Also have you tried starting the car and letting the air ride fill up completely, then getting out shutting off the air ride switch, and driving it around? It helped me diagnose if the suspension or the compressor was the problem. If you air up the system and drive around and it drops in the front your leak is coming from the front, if it drops in back its coming from the back. Ive been through almost my whole air ride system.

Your problem sounds like bad front bags, the Westar bags work very well and dont cost as much as another Mark. The only thing you have to do is enlarge the lower bolt hole slightly, I used a unibit and just barely opened the holes up with it. The Mark bolt is like a millimeter larger than the hole. My guess is they drilled the hole a standard size and the Mark bolt is Metric or the other way around. So far I havent had any failures with them. Dont keep driving it with the suspension being collapsed. I bought my 94 that way and the previous owner must have drove the hell out of it, so far Ive replaced the whole front end and most of the rear end bushings, all 4 bags and now I have to go replace the compressor because the vent seized from moisture. If you drive with leaks for a long time you collect moisture in the system and it ruins the compressor, so try to be proactive.