Bulletin No.: PIT5801C
Published date: 06/19/2023

Preliminary Information
PIT5801C Diagnostic Tip / Vehicle Sits Unlevel / Leans / Sags / Leveling
Unavailable Message / Speed Limited Message / Service Air Suspension
Message / DTC C1190 C1191 C1192 C1193 C1187 C1188 C1189 C118A C118B
C118C C118E C118F
Models
Brand:

Model:

Model Years:

VIN:
from

Engine:

to

Transmissions:

Cadillac

Escalade Models

2021 - 2023

All

All

All

All

Chevrolet

Suburban

2021 - 2023

All

All

All

All

Chevrolet

Tahoe

2021 - 2023

All

All

All

All

GMC

Yukon Models

2021 - 2023

All

All

All

All

Involved Region or Country North America
Additional Options (RPO)

F47 - Air Ride Suspension
Some customers may notice one or more of the following conditions related with the air ride
suspension.

Condition

- Vehicle suspension trim height is too high or too low at one or more corners.
- DIC Messages "Leveling Unavailable", "Service Air Suspension" and/or "Speed Limited"
- DTC's: C1190, C1191, C1192, C1193, C1187, C1188, C1189, C118A, C118B, C118C, C118E, C118F

Cause

The cause of these concerns could be an air line not being fully inserted into its air line tting at the air
springs, air controller or reservoir tank, see PIT5923A for component naming. An air line that is not
fully inserted into its tting can leak air and cause an air spring to be under in ated creating a lean/sag
to one side. But if an air line is not fully inserted at an AIR SPRING tting it could cause the air spring to
be OVER in ated. If an air spring is OVER in ated it can make the opposite side of the vehicle appear to
be low and mislead diagnosis to the side that looks like it is sagging/low. It can be hard to understand
why an air line, which is not fully inserted into the tting at the air spring, could cause an air spring to
be over in ated. The following info will provide some details on why this can happen and how to test
and diagnose this concern.
To help understand why an air line, which is not fully inserted into the tting at the air spring, can
cause an over in ated air spring you will need to understand how the air spring tting is made/works.
The air line tting, at each air spring, is unique, and contains a one way check valve within the tting.
These unique air line ttings, with the one way check valve, are ONLY used at each of the air springs.
The air line ttings at the air suspension controller and reservoir tank do not contain any check valves,
and are a straight pass through tting.
The reason the air spring ttings have this unique check valve, is to hold air pressure inside the
air spring assembly, while the air line is disconnected from the air spring. This keeps the air
spring in ated for service and manufacturing purposes. Once the air spring is installed in the vehicle
and the air line is fully inserted into the air spring tting, the end of the air line will push open and hold
open the one way check valve. This will allow air to move in or out of the air spring. When an air line is
not fully inserted into the air spring tting, it will not hold open the one way check valve. When this
happens, during an in ate command, the air can pass the one way check valve to in ate the air spring,
but the check valve will not allow air to leave during a de ate command. This will cause the air spring
to become over in ated.
Because it is critical for the air lines to be fully inserted into the air ttings, there are white marks
on each air line to indicate when the air line is fully inserted. These white marks can be useful to help
indicate that the air line is inserted far enough at the air suspension controller or reservoir tank,
but are NOT always a good indication that the are line is inserted far enough to push open the one way
check valve at the air spring tting.
The air line must be inserted into the air tting until it bottoms out AND the white marks are going into
the top of the tting. Below is a picture of an air line, at one of the air springs, which is NOT fully
inserted (1). In this case, it is evident that the white markings are not actually going into the tting. The
second photo below shows the air line after it was fully inserted (2). You can see the white marks are
now down into the top of the air line tting (2) and the air line is bottomed out in the tting.

NOTE: It is recommended to push the line into the tting as far as it will go. At least part of the white
marking MUST be into the top of the tting. Remember, when inserting an air line into an air spring
tting, just because the white marks are in the tting, does NOT always mean that the line is fully
inserted and pushing the one way check valve open.
For additional examples, see the third photo below. This is a picture of the air lines at the air
controller. In this example, there are several fully seated lines as shown in call out 4. Each of these
lines is fully seated as indicated by the fact that the white lines are partially covered by the air line
tting itself. Call out 3 is an example of a line that is not fully seated. In call out 3 you can see the white
marking is not into the air line tting as it should be.

Correction:
Note: The purpose of this PI is to focus on the air line connections at the air springs, air controller and reservoir tank. It is
understood that other issues with the air suspension system can cause over or under in ated air springs. In addition to this PI,
please follow all published SI diagnostics and safety procedures when working on the air suspension system.
In most cases, performing a very thorough inspection of each air line at the four air springs, air controller and reservoir tank will
prove to be the fastest and most fruitful way at discovering the root cause within the system. Make sure at least the white
marking on each air line is into the top of the tting and that the air line is bottomed out in the tting, as both shown and described
above. If an air line is not fully inserted, then push the air line into the tting until it is fully inserted and the white marking is into the
top of the tting. In most cases, there is no need to loosen the air line tting to fully insert the air line, just push the line info the
tting.
NOTE: Remember, when inserting an air line into an air spring tting it must be inserted fully to open the one way check valve. Just
because the white marks are into the top of the tting does NOT always mean the line is fully inserted and holding open the one way
check valve.

Continue with the following testing if the above inspection has been completed, but the vehicle is still unrepaired.
Testing for an air spring that is over in ated and will not de ate
1. Primary Test to determine if an air spring can de ate:
- Ensure the battery is fully charged
- Vehicle sitting on a at level surface with the air springs in ated
- Close all doors, hood and liftgate
- Ignition on and engine o
- Start with one corner and measure the trim height from the ground to the top of the wheel well opening for that one corner and
document the measurement.
- Use GDS2 and go into Module Diagnostics> K5 Auto Level Control Module>Control Functions > Short Term De ate > then select
the corner previously measured and perform 4 short term de ate commands.
- After completing the 4 short term de ates, for that one corner, go back and remeasure the trim height at that corner and compare
the two measurements.
- Typically, the vehicle will lower at least 10 mm's or more. If the vehicle trim height is decreasing, then continue the same steps
above for each of the remaining corners. It is important that you only do ONE corner at a time, or incorrect results will occur.
-If the vehicle does not lower after performing the 4 Short Term De ates, then suspect the air line is not fully seated at that air
spring. In some cases, if the air spring is full of air and under high pressure, it can be very di cult to push the air line into the air
tting. This is because the one way check valve is being pushed closed by the high pressure air inside the air spring. In these cases,
try lifting the vehicle by the frame so the suspension is fully extended. Then while using extreme care, push the air line into the
tting with a suitable tool. If the air line gets kinked, pinched, or damaged, it will need to be replaced.
2. Secondary Test to determine if an air spring can de ate:
- Use GDS2 and go into Module Diagnostics> K5 Auto Level Control Module>Data Display>Pressure Data and view the pressure data
for at least 5 minutes. During that 5 minutes GDS2 is polling each air spring and the reservoir tank for it's pressure reading. If an air
line is not fully inserted into one of the air spring ttings, you will notice the air pressure for that corner will be slowly decreasing
(yellow graph line, shown below) while the pressure for the other corners is holding steady.
- If the air pressure is slowly decreasing for a particular corner, as shown below, then suspect the air line at the air spring is not fully
inserted. In some cases, if the air spring is full of air and under high pressure, it can be very di cult to push the air line into the air

tting. This is because the one way check valve is being pushed closed by the high pressure air inside the air spring. In these cases,
try lifting the vehicle by the frame so the suspension is fully extended. Then while using extreme care, push the air line into the
tting with a suitable tool. If the air line gets kinked, pinched, or damaged, it will need to be replaced.

Testing for an under in ation
- Apply soapy water to the air lines and ttings at the air spring and air manifold block, while looking for any leaks. If the air
pressure is too low in the air spring, then perform the following steps to add air into the suspect corner, while inspecting for any
leaks.
- Ensure the battery is fully charged
- Close all doors, hood and liftgate
- Ignition on and engine o
- Connect GDS2 and go into the Automatic Level Control Module > Control Functions > Short Term In ate > then select the suspect
corner (LF, RF, LR, RR) and perform short term in ate commands, as needed.
Note: If the vehicle was driven for a period of time with no air pressure in an air spring, it may have damaged the air spring. Once
the vehicle is repaired, a thorough inspection of the in ated air spring should be performed. If any damage is found, or if it is
uncertain that any damage occurred, then the air spring should be replaced.

Warranty Information
For vehicles repaired under the Bumper-to-Bumper coverage (Canada Base Warranty coverage), use the following labor operation.
Reference the Applicable Warranties section of Investigate Vehicle History (IVH) for coverage information.
Labor Operation
8020980
8021000

Description
Automatic Level Control Module Replacement
Automatic Level Control Air Supply Reservoir Replacement

Labor Time
Use Published Time
Use Published Time

8044650
8044651
8033620
8033630

Rear Shock Absorber, Shock Absorber Component, Spring or Seat Air Line
Rear Shock Absorber, Shock Absorber Component, Spring or Seat Air Line - Both Sides
Front Shock Absorber, Shock Absorber Component, Spring or Seat Air Line - Left Side
Front Shock Absorber, Shock Absorber Component, Spring or Seat Air Line - Right Side

Use Published Time
Use Published Time
Use Published Time
Use Published Time

Version History
Version
Modi ed

4
11/30/2020 - Created on.
04/19/2021 - Update to warranty sections
12/08/2021 - Update to the Correction, Warranty sections and Model Years.
06/19/2023 - Update to the Models, Cause, and Correction Sections.

© 2023 General Motors. All Rights Reserved.