actuators.These outputs allow the CTM th e a bility t o
control num erous a ccessor y system s in the vehicle.
The CTM monitors its own inter nal circu itry a s
well as ma ny of its input a nd out pu t circuits, and
will store a Diagnostic Trou ble Code (DTC) in elec-
tronic m emory for any failure it detect s. Th ese DTCs
can be retrieved a nd diagn osed using a DRBIII! scan
tool. Refer to the appropriate diagnostic infor mation.
HARD WIRED INPUTS
The har d wir ed inputs to the CTM include the fol-
lowing:
• Fused B(+)
• Fused ignition switch out pu t (run-a cc)
• Fused ignition switch out pu t (run-start)
• Gr ound
• Key-in ignition switch sense
• Slidin g door switch sense
• Passenger door switch sen se
• Dr iver door switch sense
• PCI bus circuit
HARD WIRED OUTPUTS
The hard wired outpu ts of th e CTM include the fol-
lowing:
• Door lock relay output
• Door u nlock rela y out pu t
• VTSS indica tor driver
MESSAGING
The CTM uses the followin g messa ges received
from other elect ronic modu les over th e P CI dat a bus:
• Airba g Deploy (ACM)
• Beep requ est (CMTC)
• Ch arging System Failur e (PCM)
• Ch ime request (EMIC)
• Engine RPM (PCM)
• OK to Arm VTSS (PCM)
• Secu rity indicator request (SKIM)
• System Volta ge (PCM)
• Valid/Invalid Key (SKIM)
• Vehicle Dista nce (PCM)
• Vehicle Speed (PCM)
DIAGNOSIS AND TESTING - CENTRAL TIMER
MOD U L E
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, or instrument panel component diagno-
sis or service. Disconnect and isolate the battery
negative (ground) cable, then wait two minutes for
the system capacitor to discharge before perform-
ing further diagnosis or service. This is the only
sure way to disable the supplemental restraint sys-
tem. Failure to take the proper precautions could
result in accidental airbag deployment.
The hard wired in pu ts to and outpu ts from the
centr al tim er module (CTM) ma y be dia gnosed a nd
tested usin g conventiona l diagnostic tools a nd meth-
ods. Refer to t he appropriate wiring infor mation.
However, conventional diagnostic m ethods may not
pr ove conclusive in the diagn osis of the CTM. In
order to obtain conclu sive t estin g of the CTM, the
pr ogrammable com munications int erface (PCI) dat a
bus networ k and all of the modules t hat provide
input s to or receive output s from t he CTM mu st a lso
be checked. The most reliable, efficien t, an d accurat e
mean s t o diagnose th e CTM, the PCI da ta bus net -
work, and t he modu les tha t provide input s t o, or
receive outpu ts from, the CTM r equires th e use of a
DRBII I! scan tool. Refer to the appropriate diagnos-
tic information.
REMOVAL
(1) Disconn ect and isolate the battery nega tive
cable.
(2) Slide t he driver seat to the full for ward posi-
tion.
(3) Disconn ect th e wire ha rness con nector for t he
seat belt lat ch. (Fig. 1).
(4) Remove t he scr ews that secure the closeout
pa nel beneathe th e dr iver sea t cushion and remove
the panel.
(5) Remove the screws that secu re t he cent ral
timer module to the bra cket .
(6) Disconn ect t he wire harness connect ors fr om
the centr al t imer module.
(7) Remove the centr al timer module from the
vehicle.
8E - 2 ELECTRONIC CONTROL MODULES VA
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