1999 PCED On Board Diagnostics II |
SECTION 5: Pinpoint Tests |
JH1 CHECK CTO CIRCUIT FOR SHORT TO POWER IN HARNESS
- Disconnect PCM.
- Key on, engine off.
- Measure voltage of CTO circuit between PCM harness connector pin 48 and
ground.
Is the voltage less than 0.5 volt?
|
Yes
|
No
|
|
KEY OFF. GO to JH2
.
|
REPAIR short circuit. VERIFY symptom no longer exists.
|
JH2 CHECK CTO CIRCUIT FOR SHORT TO GROUND IN HARNESS
- Disconnect instrument cluster connector.
- Measure resistance between PCM harness connector pin 48 and battery
negative post.
- Measure resistance between PCM harness connector pin 48 and chassis
ground.
Are both resistances greater than 10,000 ohms?
|
Yes
|
No
|
|
GO to JH3
.
|
REPAIR short circuit. VERIFY a symptom no longer exists.
|
JH3 CHECK CTO CIRCUIT FOR OPEN IN HARNESS
- Measure resistance between PCM harness connector pin 48 and instrument
cluster harness pin.
Is the resistance less than 5.0 ohms?
|
Yes
|
No
|
|
GO to JH4
.
|
REPAIR open circuit. VERIFY symptom no longer exists.
|
JH4 CHECK CTO SIGNAL FROM PCM
- Reconnect PCM.
- Start engine.
- Measure voltage between CTO pin at the instrument cluster and battery
negative post.
Is voltage between 3.0 and 9.0 volts?
|
Yes
|
No
|
|
GO to the Instrument Cluster, Section 413-01 in Workshop Manual for
diagnosis and testing.
|
REPLACE PCM (refer to Section 2
, Flash EEPROM).
|
JH: Introduction