7A1–76 AUTOMATIC TRANSMISSION (4L30-E)
DIAGNOSTIC TROUBLE CODE (DTC) 21
THROTTLE POSITION SENSOR SHORT TO PLUS
This DTC flashes the CHECK TRANS indicator and
sets the BACKUP MODE.
Circuit Description:
•
The Throttle Position Sensor (TPS) provides a
voltage signal that changes relative to the throttle
plate position. Signal voltage between connector
C-95 terminals C5 and C6 will vary from about 0.4
at idle to about 4.6 volts at wide open throttle.
•
The Engine Control Module (ECM) also receives
this signal. This TPS is a variable resistance with
one side (connector E-68 terminal 1) connected
only to the ECM connector to have the 5 volts
supply voltage. The other side (connector E-68
terminal 3) is connected to the Transmission
Control Module (TCM) (floating ground) and the
ECM (ground). The “middle” (the wiper) (con-
nector E-68 terminal 2) is connected to the TCM
and the ECM.
•
The ECM monitors output voltage from the TPS
and determines fuel delivery based on throttle
valve angle (driver demand).
•
This TPS is an electrical component and must not
be soaked in any liquid cleaner or solvent, as
damage may result.
Diagnostic Aids:
•
This Diagnostic is an electrical test done by the
TCM.
•
Detection conditions:
1 Voltage between connector C-95 terminals C5
and C6 > 4.9 volts. This detection occurs
when: The wiper is short to voltage (engine
can stall).
2 The condition needs to be present for at least
0.5 seconds. Note: during the detection time
the TCM reads “100% (wide open throttle)”.
•
Action after the detection time: BACKUP MODE.
•
Recovery conditions: To recover when voltage <
or = to 4.9 volts and do an IGNITION CYCLE.
TPS
INPUT
GROUND
TRANSMISSION
CONTROL
MODULE(TCM)
C-95
C5(5)
5
H-25
3
C6(6)
GRN
BLU
BLU
BLU
BLU
GRN
27
5VOLT
REFERENCE
TPS
INPUT
GROUND
GRY
GRY
GRY
THROTTLE
POSITION
SENSOR
(TPS)
ENGINE
CONTROL
MODULE
(ECM)
26
39 E-61
E-68
E-68
E-68
2
1
3
D07LW009