ELECTRONIC CONTROL MODULES
TAB LE O F CO NTE NTS
page page
CENTRAL TIMER MODULE
DESCRIPTION ..........................1
OPERATION ............................1
DIAGNOSIS AND TESTING - CENTRAL TIMER
MODULE .............................2
REMOVAL .............................2
INSTALLATION ..........................3
CONTROLLER ANTILOCK BRAKE
DESCRIPTION ..........................3
REMOVAL .............................3
INSTALLATION ..........................3
ENGINE CONTROL MODULE
DESCRIPTION ..........................3
REMOVAL .............................6
INSTALLATION ..........................6
TRANSMISSION CONTROL MODULE
DESCRIPTION ..........................6
OPERATION ............................7
STANDARD PROCEDURE - TCM ADAPTATION . 10
CEN T RAL T I M ER M ODU LE
DESCRIPTION
The cent ral timer m odu le (CTM) is located benea th
the dr iver seat . The CTM uses inform ation car ried on
the program mable comm unications in terfa ce (P CI)
da ta bu s networ k a long with m any hard wir ed inputs
to monitor many sensor a nd swit ch in pu ts. In
response to those inputs, t he circuitry and program -
ming of th e CTM allow it to su pply the veh icle occu-
pa nts wit h audible an d visual in formation, and to
control and in tegr ate man y fu nctions and feat ures of
the vehicle thr ough bot h ha rd wir ed outpu ts and t he
transmission of message out puts to other modules in
the vehicle over th e PCI dat a bus.
The fea tures t hat th e CTM supports or con trols
include the following:
• Ce nt ra l Lo c k i n g - Th e CTM on vehicles
equipped with the optional Vehicle Theft Security
System (VTSS) inclu des a centr al locking/unlocking
featu re.
• Enhanced Accident Response - The CTM pro-
vides an optional enha nced accident r esponse fea -
ture. This is a progr ammable featu re.
• Panic Mode - The CTM provides support for
the opt ional RKE syst em pan ic mode includin g horn,
headlamp, a nd park la mp flash fea tures.
• Power Lock Control - The CTM provides the
opt ional power lock system feat ures, in cluding sup-
por t for the au tomatic door lock a nd door lock in hibit
modes.
• Programmable Features - The CTM pr ovides
su pport for cer tain pr ogrammable fea tures.
• Remote Keyless Entry - The CTM provides
the optional Remote Keyless Entry (RKE ) system fea-
tures, inclu ding support for the RKE Lock (with
opt ional hor n a nd pa rk la mps flash), Unlock (with
pa rk lamps fla sh , driver-door-only u nlock, and
unlock-a ll-doors), P anic, and illu minated entry
modes, as well a s t he ability to be program med to
recogn ize up to four RKE tr ansmitter s. The RKE
horn, driver-door-only unlock, and unlock-a ll-doors
featu res ar e progr amma ble.
• Ve h i c l e T h e f t S e c u r i t y S y s t e m -TheCTM
pr ovides contr ol of the opt ional Vehicle Theft Secu -
rity System (VTSS) fea tures, includin g support for
the centr al locking/unlocking mode and con trol of th e
Security indicator in the instrumen t cluster.
Hard wired circuitr y connects the CTM to th e elec-
trical system of the vehicle. Refer to the appropriate
wiring infor mat ion.
Many of the features in the vehicle controlled or
su pported by the CTM are program mable using the
DRBII I! sca n tool. However, if any of t he CTM ha rd-
ware components a re da maged or fau lty, the ent ire
CTM unit must be r eplaced. The hard wired in pu ts
or outputs of all CTM versions can be diagnosed
using conventional diagn ost ic tools and methods;
however, for diagn osis of the CTM or t he PCI data
bus, the use of a DRBIII! scan tool is required. Refer
to th e appropriate diagnostic in formation.
OPERATION
The central t imer module (CTM) monitors man y
hard wired switch and sen sor in pu ts as well as t hose
resources it sh ares with oth er modules in th e vehicle
through its commu nica tion over th e pr ogra mmable
communicat ions in terface (PCI) data bus network.
The inter nal pr ogra mming and all of these inputs
allow the CTM to det ermine t he ta sks it needs to
perform an d their prior ities, as well as bot h t he st an-
da rd a nd optional featu res t hat it should provide.
The CTM th en performs those tasks an d pr ovides
those features throu gh both PCI data bu s com muni-
cation with oth er modules an d hard wired outputs
through a num ber of driver circuits, relays, and
VA ELECTRONIC CONTROL MODULES 8E - 1
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