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 – 2021 Cadillac Chevrolet GMC

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Bulletin No.: PIT5801A Published date: 04/19/2021
Preliminary Information
PIT5801A 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:

Cadillac Chevrolet Chevrolet GMC

Model:

Escalade Models Suburban Tahoe
Yukon Models

Model Years:

2021
2021
2021
2021

VIN:
from to
All All
All All
All All
All All

Engine:

All All All All

All All All All

Transmissions:

Involved Region or Country Additional Options (RPO)

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

– 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 one or more of the air lines not being fully seated into an
air spring or air manifold block assembly. An air line that is not fully seated can cause the air
spring to be either over inflated or under inflated.
It can be easy to understand and explain why an air line that is not fully seated can cause an air
spring to be under inflated, due to the air leaking out, but over inflated air springs will require
some additional details. The air springs use a unique air line fitting that contains a one way
check valve. This one way check valve was needed for manufacturing purposes to keep a small amount
of air inside the air
spring before it is installed on the vehicle. Once the air spring is installed in the vehicle and
the air line is fully seated into the air spring fitting, the one way check valve is no longer
needed and the air line holds the check valve open. If the air line is not fully seated into the
fitting, it will not fully open the one way check valve.
When this happens, air can be pushed past the one way check valve into the air spring, but air can
not be released. This will cause the air spring to inflate but during a deflate it cannot release
the air from inside the air spring.
Because it is critical for the air lines to be fully seated into the air fittings, there are white
marks on each air line to indicate when the air line is fully seated. The air line has to be
inserted into the air fitting until it bottoms out AND the white marks are going into the top of
the fitting. Below is a picture of an air line, at one of the air springs, which is NOT fully
seated (1). This is indicated by the white markings not actually going into the fitting. The
second photo below shows the air line after it was fully seated (2). You can see the white marks
are now down into the top of the air
line fitting (2) and the air line is bottomed out in the fitting.

NOTE: It is recommended to push the line into the fitting as far as it will go. At least part of
the white marking MUST be into the top of the fitting.

For additional examples see the third photo below. This is a picture of the air lines at the air
manifold block. In this example, there are several fully seated lines as shown in call out 4.
Each of these lines are fully seated as indicated by the white markings being into the top of the
air line fitting. 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 fitting as it should be.

Correction:
Note: The purpose of this PI is to focus on the air line connections at the air shocks and air
manifold block. It is understood that other issues with the air suspension system can cause over
or under inflated air springs. In addition to this PI, please follow all published SI diagnostics
and safety procedures when working on the air suspension system.

Typically, performing a very thorough inspection of each air line at the four shocks and manifold
valve block will prove to be the most fruitful way at discovering the root cause within the system.
Make sure the white
marking on each air line is into the top of the fitting and that the air line is bottomed out in
the fitting, as both shown and described above. If an air line is not fully seated, then push the
air line into the fitting until it is fully seated and the white marking is into the top of the
fitting. In most cases, there is no need to loosen the air line fitting to fully seat the air
line.
Perform the following test to ensure the air lines are fully seated:

1. To test for an air spring that will not deflate due to the air line not being fully seated into
the air spring, perform the following test:

If this condition exists, suspect the side or corner that is sitting higher than the others. For
example, if the vehicle sits high on the left side, then suspect the left side air springs are not
able to deflate.

– Ensure the battery is fully charged
– Close all Doors, Hood and Liftgate
– Ignition on and engine off
– Connect GDS2 and go into the Automatic Level Control Module > Data Display > Automatic Level
Control System Data and note the suspect corner’s “Position Offset from Trim” shown in millimeters
(mm). Note: The units button in GDS2 may have to be selected to change from cm to mm.
– Once the “Position Offset from Trim” is noted for the suspect corner, then use GDS2 and go into
Control Functions > Short Term Deflate > then select the suspect corner (LF, RF, LR, RR) and
perform two short term deflate commands.
– Once complete, use GDS2 and go back into Data Display > Automatic Level Control System Data and
note the suspect corner’s “Position Offset from Trim” again. Typically, the vehicle will lower 5
to 8 mm’s. If the vehicle does not lower after performing the Short Term Deflates, then suspect
the air line is not fully seated at the air spring. In some cases, if the air spring is full of
air and under high pressure, it can be very difficult to push the air line into the air fitting.
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 and/or if necessary, while using extreme care, push the air line into the fitting with a
suitable tool. If the air line gets kinked, pinched, or damaged, it will need to be replaced.

2. To test for an under inflation condition where the air line is not fully seated and leaking
air, perform the following test:

If this condition exists, then suspect the side or corner that is low. Example, if the vehicle
sits very low on the left side then suspect that the left side air spring lines may be leaking.
– Apply soapy water to the air lines and fittings 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 off
– Connect GDS2 and go into the Automatic Level Control Module > Control Functions > Short Term
Inflate > then select the suspect corner (LF, RF, LR, RR) and perform short term inflate 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 inflated
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 warranty, please use the appropriate warranty labor operation based on
the repair needed, see below.

Labor Operation
8020980

2811255

8021000

8044650

8044651

8033620

8033630

Description

Automatic Level Control Module Replacement

K5 Automatic Level Control Module Reprogramming with SPS Automatic Level Control Air Supply
Reservoir Replacement
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

Labor Time
Use Published Time
Use Published Time
Use Published Time
Use Published Time
Use Published Time
Use Published Time
Use Published Time

Version History
Version 2
Modified 11/30/2020 – Created on.
04/19/2021 – Update to warranty sections

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