FIELD SERVICE BULLETIN

Freightliner M2
[ ] Safety Recall
[ ] Field Campaign
[ ] Service Information
[X] Product Improvement

ADA Parking Brake Interlock
addition

FSB_2012-102
Revision: 0
Issue Date: 12/11/2012
Manual Section: N/A
Author: M. Neuville
Approval: B. Sprague
Form Rev. C 06/04/09

UNITS AFFECTED: 22732 through 22753, and 22755.
DESCRIPTION: The valve added by this bulletin will prohibit the parking brake from being
released when the wheelchair lift is deployed, providing additional redundancy to the ADA lift
interlock.
CAMPAIGN EXPIRATION DATE: No expiration date
MATERIALS NEEDED:
Part Number
3972585
3975938
3974628
3941796
3945623

Description
Quantity
VALVE, SOLENOID ELECTRIC INTERLOCK
1
HARNESS, INTERLOCK PB M2
1
RELAY, 40 AMP 12 VOLT SPEMCO
1
LOOM,3/4" NYLON W/STRIPE HI-TEMP
1 FT
LOOM,1/4SPLIT NYLON W/STRIPE ALL
1 FT
Male ¼” spade terminals
Female ¼” spade terminals
Zip ties

DISCLAIMER:
The procedures contained herein are not exclusive. Champion Bus, Inc. cannot possibly know,
evaluate, or advise the transportation industry of all conceivable ways in which a procedure may
be undertaken or of the possible consequences of each such procedure. Other procedures may be
as good, or better, depending upon the particular circumstances involved.
Each carrier who uses the procedures herein must first satisfy itself thoroughly that neither the
safety of its employees or agents, nor the safety of any products, will be jeopardized by any
procedure selected.
PROCEDURE:
1. Park the bus in a level location, place the gear selector in PARK, apply the parking
brakes, and chock the wheels.
2. Move the curbside mirror out of the way and open the Freightliner hood.

FSB 2012-102

Page 1 of 7

3. On the roadside of the vehicle, locate the bundle of air lines where they pass through the
firewall.

4. Locate the black 3/8” air line. This is the delivery line for the parking brake (spring
brake) system. First ensure the parking brake is still applied (knob out), then remove the
quick-disconnect splice fitting.

Disconnect fitting
and remove

Black
delivery line

FSB 2012-102

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5. Install the provided valve such that the black line from the firewall is connected to the
port labeled “EXH” and the black line from beneath is connected to the port labeled
“OUT”. It may be helpful to trim the existing line by an inch for the new valve to fit.
TO FIREWALL

IN

EXH

OUT

Valve installed
in-line

FSB 2012-102

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6. Secure the valve to the surrounding bundle of air lines using zip-ties. Avoid using zip
ties directly on air lines. Instead, zip tie to plastic or metal fittings wherever possible.
Use loom to protect any air lines the valve body contacts.

New loom
protects this air
line from valve
contact.

This zip tie places
its load on loom
and a metal fitting.

7. At this time, you may test the valve for
proper plumbing by pressing the red
button on the valve. With wheels
chocked and vehicle in park, pressing
the valve’s red button should result in
the parking brakes applying. When
satisfied, re-apply the parking brake
using the dashboard knob.
8. Protect the two wires on the valve with
loom, and use electrical tape at each
end to secure the loom to the wires.
On the rubber pass-through at the
firewall, poke out the plug for the
largest available opening. Run the
loomed wires through this opening.

FSB 2012-102

Run loomed
wires through
this hole

Page 4 of 7

9. Inside the bus, under the dashboard, crimp female quick-disconnect terminals to the two
black wires from the valve.
10. Locate the Intermotive module and range inhibit relay to prepare for installation of the
retrofit harness. The Intermotive is located to the left of the steering column on the
firewall. The range inhibit relay is within a few inches of the Intermotive module.

Range
inhibit
relay

Intermotive
module

FSB 2012-102

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11. A blue wire runs from pin 8 of the 12-pin connector on the Intermotive, to pin 85 or 86 of
the range inhibit relay. Cut this blue wire and crimp on terminals such that the side of the
relay has two wires in its terminal, effectively creating a wye. The new wire at the
connection goes to the blue wire from pin 85 or 86 of the new relay.
Inhibit
relay base

Blue wire from
new relay

New connection
12 6
Intermotive
plug
8
1

12. Above the steering column, find connector C187. Pin 3 is unused on one side. Connect
the red wire from the new relay in the retrofit harness to pin 3.

Red wire from
new relay

C187
1
2
3
4

FSB 2012-102

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13. Crimp male quick-disconnect terminals onto the remaining blue and green wires from the
retrofit harness. Connect the blue and green wires to the black wires from the valve.
Polarity does not matter.

14. Connect the ring terminal that is part of the green wire to an existing nearby ground
location.
15. The overall connection of the retrofitted wiring is demonstrated below.
Step
11

Step
13
Step
12
Step
14

16. Use zip-ties to secure the wires under the dash out of the way. Ensure that there will be
no chance of the wires interfering with pedal operation or the movement of driver’s feet.

FSB 2012-102

Page 7 of 7