IGNITION CONTROL
TAB LE O F CO NTE NTS
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IGNITION CONTROL
OPERATION - GLOW PLUG ................1
SPECIAL TOOLS ........................1
GLOW PLUG
REMOVAL .............................1
INSTALLATION ..........................1
GLOW PLUG RELAY
DESCRIPTION ..........................1
OPERATION ............................2
DIAGNOSIS AND TESTING - GLOW PLUG
RELAYS ..............................2
IGNITION CONTROL
OPERATION - GLOW PLUG
Pre - Glowing
With t he key in t he On position, the glow plug out-
pu t sta ge and t he indica tor lam p are act uated by th e
ECM. The pre-heating tim e is calculated by the E CM
in line with t he coolant temperatur e. Th e glow plu g
output stage switches the curr ent t hrough the glow
plugs. The glow plu g in dicator lamp goes out after a
pr e-glow per iod has elapsed. Componen t or ca ble fail-
ures in th e pre-glow system a re indica ted by t he glow
plug lam p and stor ed in the ECM.
Glow Output Stage
With the ign ition key in the On position a signa l is
transmit ted fr om t he ECM to th e glow plug output
st ager. If no dat a is excha nged wit h th e ECM th e
glow plug stage is term inated after two seconds. The
glow plug out put stage constan tly signals the cur-
rent operat ing st ate (ON/OF F) and any syst em
faults. Th e following faults ar e recognized by the out
put st age a nd t ra nsm itted to t he ECM:
• Open circuit in on e or more of the glow plug
lead s
• Short circu it in th e glow plug cir cuit
• Ou t put stage fa ult or t empera tur e relat ed shut -
off
If a failure in the glow plug syst em occurs, th e
glow plug indica tor la mp will be illumina ted on ly as
long as the fault is current. If the fa ilu re is no longer
pr esent, th e glow plug indica tor lamp will be
switch ed off but a code will be stor ed in th e ECM.
After Glow
Once the en gin e ha s sta rted, the ECM det ermines
the a fter glow tim e dependin g on cooling t empera -
ture. During this time the glow plu gs cont inue to be
actuated by t he glow plug out pu t stage. This resu lts
in improved sm ooth runn ing after a cold st art and
improved warming up pr operties, elim ina tion of blue
exha ust aft er a cold sta rt up and a more stable cold
star ting speed.
If no signal is received from the coolant t empera -
ture sen sor the sign al from the oil sen sor is used a s a
substitu te.
SPECIAL TOOLS
GLOW PLU G
REMOVAL
(1) Disconn ect the n egat ive battery cable.
(2) Remove the engine cover.
(3) Use special tool #9286 plier s to unplug the
glow plug wir ing har ness conn ector(s) at the glow
plug.
(4) Remove the glow plug(s) (Fig. 1).
INSTALLATION
(1) Scr ew glow plug(s) in to cylin der head a nd
tighten to 12 N·m (115 lbs. in) (Fig. 1).
(2) Connect the glow plug wiring harness connec-
tor(s)
(3) In st all the engine cover.
(4) Connect nega tive bat tery cable.
GLOW PLU G RELAY
DESCRIPTION
The glow plu g rela y supplies battery volta ge to t he
glow plu g throu gh a tim ed cycle tha t is relat ed to
coolan t tempera ture. The glow plug rela y is located
under the battery. The purpose of a glow plug system
GLOW PLUG PLIERS
VA IGNITION CONTROL 8I - 1
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