DIAGNOSTICS
SERVICE MANUAL NUMBER 24
Page 5G-60
90-861327--1 OCTOBER 1999
Code 21 (3 of 3): Throttle Position (TP) Sensor Circuit
Step
Action
Yes
No
PROCEED TO
a. Ignition OFF.
b. Connect a test light to battery positive (B+).
9.
c. Touch test light to harness terminal “C” (throttle position
sensor signal).
Is test light on?
Step 12. Step 15.
10.
Connect DVOM between harness terminal “C” and
engine ground (–).
10.
Is voltage reading over 4 volts?
Step 13. Step 14.
11.
Connect DVOM from throttle position sensor harness ter-
minal “A” to a good ground on engine.
11.
Is voltage reading over 4 volts?
Step 18. Step 17.
a. Disconnect ECM.
12.
b. Touch test light to harness terminal “C” (throttle position
sensor signal).
Is test light on?
Step 16. Step 14.
13.
Check for CKT 417 shorted to voltage.
–
–
14.
Locate and repair open in CKT 417 or faulty connection
at ECM.
–
–
15.
Replace throttle position sensor.
–
–
16.
Check for CKT 417 shorted to ground.
–
–
17.
CKT 416 open or shorted to ground or faulty connection
at ECM.
–
–
18.
CKT 813 open faulty connection at ECM.
–
–
Index