Dodge D150 1990 Service Manual page 704

perature d u r i n g a l l operating modes. M a i n t a i n i n g
correct sensor temperature a t a l l times allows t h e
system t o enter i n t o closed loop operation sooner.
I n "Closed Loop" operation t h e SBEC monitors the
0
2
sensor i n p u t (along w i t h other inputs) a n d adjusts
t h e injector pulse w i d t h accordingly. D u r i n g "Open
Loop" operation t h e SBEC ignores t h e 0
2
sensor i n -
p u t a n d adjusts injector pulse w i d t h t o a prepro-
grammed value (based o n other sensor inputs).
Fig. 7 Heated Oxygen Sensor Location—3.9L
Engine
4-WAY HEATED 0
2
SENSOR HEATED Oj SENSOR
Fig. 8 Heated Oxygen Sensor Location—5.2L and
5.9L Engines
THROTTLE BODY TEMPERATURE SENSOR-SBEC
INPUT (5.2L and 5.9L Engines)
Vehicles equipped w i t h a 5.2L o r 5.9L engine have
a t h r o t t l e body temperature sensor. T h e sensor (Fig.
9) monitors t h r o t t l e body temperature w h i c h is the
same as fuel temperature. I t is m o u n t e d i n the throt-
t l e body. This sensor provides i n f o r m a t i o n o n fuel
temperature w h i c h allows the SBEC t o enrichen t h e
a i r fuel m i x t u r e for a h o t restart condition.
J9014473
Fig. 9 Throttle Body Temperature Sensor
THROTTLE POSITION SENSOR (TPS)-SBEC
INPUT
The T h r o t t l e Position Sensor (TPS) is mounted o n
the t h r o t t l e body below t h e M A P sensor a n d con-
nected t o the t h r o t t l e blade shaft (Fig. 10). T h e TPS
is a variable resistor t h a t provides t h e Single Board
Engine Controller (SBEC) w i t h a n i n p u t signal (volt-
age) t h a t represents t h r o t t l e blade position. A s t h e
position o f the t h r o t t l e blade changes, the resistance
of the TPS changes.
The SBEC supplies approximately 5 volts t o t h e
TPS. T h e TPS o u t p u t voltage ( i n p u t signal t o t h e
SBEC) represents t h e t h r o t t l e blade position. T h e
SBEC receives a n i n p u t signal voltage from t h e TPS
v a r y i n g i n a n approximate range o f from 1 v o l t a t
m i n i m u m t h r o t t l e opening (idle) t o 4 volts a t wide
open t h r o t t l e . A l o n g w i t h i n p u t s f r o m other sensors,
the SBEC uses t h e T P S i n p u t t o determine c u r r e n t
engine operating conditions a n d adjust fuel injector
pulse w i d t h a n d i g n i t i o n t i m i n g .
MAP SENSOR
SENSOR (TPS) J9014-157
Fig. 10 Throttle Position Sensor