Chk Susp 99 Eb
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From: Santo Domingo, Dom. Rep.
Chk Susp 99 Eb
CHK SUSP light comes on after half hour of driving.
When start it pumps up, after rolling it pumps up, then half an hour later while driving the chk susp light comes on. There are no leaks, vehicle stays pumped up. Vehicle stays pumped up overnight. Soapy water shows no leaks. I changed the comp last week to a rebuilt from American Air Susp and it still does exactly the same. I did not change the relay since I figure it is only an on/off switch and if it works at startup it is OK. If I restart it is good for half hour, if a friend resets the susp switch passenger side while driving, the light goes off and comes back on in half an hour. The comp only runs once or twice in the half hour for 15 or 20 sec. then the light comes on. All systems seem to work fine, 4/4 pumps up more, 4/4 low pumps up even more. Switch off, vehicle drops to correct level.
When start it pumps up, after rolling it pumps up, then half an hour later while driving the chk susp light comes on. There are no leaks, vehicle stays pumped up. Vehicle stays pumped up overnight. Soapy water shows no leaks. I changed the comp last week to a rebuilt from American Air Susp and it still does exactly the same. I did not change the relay since I figure it is only an on/off switch and if it works at startup it is OK. If I restart it is good for half hour, if a friend resets the susp switch passenger side while driving, the light goes off and comes back on in half an hour. The comp only runs once or twice in the half hour for 15 or 20 sec. then the light comes on. All systems seem to work fine, 4/4 pumps up more, 4/4 low pumps up even more. Switch off, vehicle drops to correct level.
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
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From: Lorain County, Ohio
It's telling you that you have a big leak. Most likely in the rear air springs.
The light usually won't come on unless there is a leak that the compressor can't keep up with. The compressor can't keep up with the leakage while you're driving.
The compressor is not desgned to "keep up " with ANY leakage in the system. It's longevity requires that the air system be tight.
Leaks in the rear air springs often won't show up unless you're driving. The bladders roll under thenselves at the bottom and cracks develop under the "fold". They only leak when the suspension moves. Those leaks quickly become overnight leaks. Replace the rear air springs. About $230 per pair from Arnott Industries.
The light usually won't come on unless there is a leak that the compressor can't keep up with. The compressor can't keep up with the leakage while you're driving.
The compressor is not desgned to "keep up " with ANY leakage in the system. It's longevity requires that the air system be tight.
Leaks in the rear air springs often won't show up unless you're driving. The bladders roll under thenselves at the bottom and cracks develop under the "fold". They only leak when the suspension moves. Those leaks quickly become overnight leaks. Replace the rear air springs. About $230 per pair from Arnott Industries.
Originally Posted by Byron43
CHK SUSP light comes on after half hour of driving.
When start it pumps up, after rolling it pumps up, then half an hour later while driving the chk susp light comes on. There are no leaks, vehicle stays pumped up. Vehicle stays pumped up overnight. Soapy water shows no leaks. I changed the comp last week to a rebuilt from American Air Susp and it still does exactly the same. I did not change the relay since I figure it is only an on/off switch and if it works at startup it is OK. If I restart it is good for half hour, if a friend resets the susp switch passenger side while driving, the light goes off and comes back on in half an hour. The comp only runs once or twice in the half hour for 15 or 20 sec. then the light comes on. All systems seem to work fine, 4/4 pumps up more, 4/4 low pumps up even more. Switch off, vehicle drops to correct level.
When start it pumps up, after rolling it pumps up, then half an hour later while driving the chk susp light comes on. There are no leaks, vehicle stays pumped up. Vehicle stays pumped up overnight. Soapy water shows no leaks. I changed the comp last week to a rebuilt from American Air Susp and it still does exactly the same. I did not change the relay since I figure it is only an on/off switch and if it works at startup it is OK. If I restart it is good for half hour, if a friend resets the susp switch passenger side while driving, the light goes off and comes back on in half an hour. The comp only runs once or twice in the half hour for 15 or 20 sec. then the light comes on. All systems seem to work fine, 4/4 pumps up more, 4/4 low pumps up even more. Switch off, vehicle drops to correct level.
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From: Santo Domingo, Dom. Rep.
lsrx101
If it were a leak the comp would run trying to keep up and it doesn't. I can drive many hours with the chk susp light on and have no rear droop. I raised it to the top with 4/4 low turn the system off and it maintained its height overnight. I put a led light to the comp and can monitor when it is on. It turns on when I start the engine and close the door for about 20 sec. again when I start rolling for about 30 sec., 10 to 15 minutes later it runs again for about 15 sec., then 15 to 20 min later without running again the chk susp light comes on. I would understand airspring leak if the comp ran more. Any way I will ck them again. Thanks for your imput.
If it were a leak the comp would run trying to keep up and it doesn't. I can drive many hours with the chk susp light on and have no rear droop. I raised it to the top with 4/4 low turn the system off and it maintained its height overnight. I put a led light to the comp and can monitor when it is on. It turns on when I start the engine and close the door for about 20 sec. again when I start rolling for about 30 sec., 10 to 15 minutes later it runs again for about 15 sec., then 15 to 20 min later without running again the chk susp light comes on. I would understand airspring leak if the comp ran more. Any way I will ck them again. Thanks for your imput.
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From: Santo Domingo, Dom. Rep.
Spent half a day Sat monitoring the suspension. At startup it pumps up fine and the compresor turns off after the truck reaches its runninig level. About ten minutes later there is a clicking sound at the compressor and the front end starts to drop. When it drops the front end about an inch the compressor comes on again and pumps it up. Ten minutes later the click again and it drops, it seems to vent presure from the compressor. On the third or fourth sequence the CK susp light comes on. The click seems to be the same as when you turn the vehicle off and it vents and lowers except it does it while running and only the front. Could this be programming???
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From: Santo Domingo, Dom. Rep.
I agree about getting the codes. My scanner won't read them. Instead of paying dealer $200 to read and exagerate the problem, I am looking at scanners that will. Has anyone tried AutoEnginuity's Scan Tool. With the Ford enhanced programming it should do.
Logistics Pro
Joined: Jan 2001
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From: Central NYS
The scan tool software I've been using is by AutoDiag by Auterra. It runs on my PDA and will graph O2 sensor output, etc,etc. But it is not bi-directional.
(Bi-directional allows you, through the scan tool, to do things like run the driver's window down, beep the horn (nice for diagnosing electrical issues, i.e, if the window goes down when commanded by the scan tool you know the window motor and its power and ground is in tact and the problem must be in the switching circuits), etc. It'd be nice to command the LLS to vent the sytem when you need to work on it.)
Auterra has been telling me they will have bi-directional control for 2 years now and I haven't seen it yet. So I'm looking for a better scan tool.
Let me(us) know what you think of the AutoEnginuity's capabilities
(Bi-directional allows you, through the scan tool, to do things like run the driver's window down, beep the horn (nice for diagnosing electrical issues, i.e, if the window goes down when commanded by the scan tool you know the window motor and its power and ground is in tact and the problem must be in the switching circuits), etc. It'd be nice to command the LLS to vent the sytem when you need to work on it.)
Auterra has been telling me they will have bi-directional control for 2 years now and I haven't seen it yet. So I'm looking for a better scan tool.
Let me(us) know what you think of the AutoEnginuity's capabilities
