At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
You have a wiring problem from sensor to the PCM - engine computer .
DL22 CHECK CHT SIGNAL CIRCUIT FOR SHORT TO GROUND
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.
Disconnect PCM.
Measure resistance between CHT signal and SIG RTN circuits and then between CHT signal and PWR GND circuits at the PCM harness connector.
the PCM is what controls the cooling fan !
This Pinpoint Test is intended to diagnose the following:
Cylinder head temperature (CHT) sensor (6G004)
Harness circuits: CHT, VREF, and SIG RTN
Powertrain control module (PCM) (12A650)
Tables and Graphs
On applications that do not use a ECT sensor, the CHT sensor is used to determine the engine coolant temperature in place of the ECT sensor. In this case the PCM may store both CHT and ECT Diagnostic Trouble Codes (DTCs). To cover the entire temperature range of both the CHT and ECT sensors, the PCM has a dual switching resistor circuit on the CHT input. A graph showing the temperature switching from the COLD END line to the HOT END line with increasing temperature and back with decreasing temperature is included. Note the temperature to voltage overlap zone. Within this zone it is possible to have either a COLD END or HOT END voltage at the same temperature. For example, at 90°C (194 °F) the voltage could read either 0.60 volt or 3.71 volts. Refer to the table for the temperature to voltage expected values.
Voltage values were calculated for VREF = 5.0 volts. These values can vary 15 percent due to sensor and VREF variations.
DL1 DTC P1288 OR P1116: CHECK OPERATION OF CYLINDER HEAD TEMPERATURE SENSOR
Run engine at 2000 rpm until engine temperature becomes stabilized.
No Starts or Vehicle that Stalls:
GO to DL3 .
Check that upper radiator hose is hot and pressurized.
Rerun Key On Engine Running (KOER) Self-Test.
Is DTC P1288 or P1116 present?
Yes
No
GO to DL2 .
Engine temperature was not stabilized. REPAIR any other DTCs as necessary.
DL2 CHECK VREF CIRCUIT VOLTAGE AT TP SENSOR
Refer to schematic at the beginning of this pinpoint test.
Disconnect throttle position (TP) sensor.
Key on, engine off.
Measure the voltage between VREF and SIG RTN circuits at the TP sensor harness connector.
Is voltage between 4.0 volts and 6.0 volts?
Yes
No
There is sufficient VREF voltage. RECONNECT TP sensor. GO to DL3 .
GO to C1 .
DL3 CHECK RESISTANCE OF CYLINDER HEAD TEMPERATURE SENSOR WITH ENGINE OFF
Disconnect CHT sensor.
Measure resistance between CHT signal and SIG RTN pins at the CHT sensor. Refer to the table at the beginning of this pinpoint test for resistance specifications.
Is resistance within specification?
Yes
No
For No Starts or Stalls, RETURN to Section 3 , Symptom Charts.
All others, GO to DL4 .
REPLACE CHT sensor.
You need a scan tool to do some of these tests
DL4 CHECK RESISTANCE OF CHT SENSOR WITH ENGINE RUNNING
Note: Verify that engine is at operating temperature before taking CHT readings.
Run engine for two minutes at 2000 rpm.
Measure resistance between CHT signal and SIG RTN pins at the CHT sensor. Refer to the table at the beginning of this Pinpoint Test for resistance specifications.
Key off.
Is resistance within specification?
Yes
No
REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ).
REPLACE CHT sensor.
DL5 DTC P1289 OR P1290: ACCESS CHT PID AND CHECK VOLTAGE
Connect scan tool.
Key on, engine off.
Access CHT V PID.
Is the CHT V PID less than 0.2 volt?
Yes
No
GO to DL6 .
GO to DL7 .
DL11 CHECK CHT SENSOR SIGNAL AND SIG RTN CIRCUITS FOR OPEN IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.
Disconnect PCM.
Measure resistance of CHT circuit between PCM harness connector pin and CHT sensor harness connector.
Measure resistance of SIG RTN circuit between PCM harness connector pin and CHT sensor harness connector.
Is each resistance less than 5.0 ohms?
Yes
No
REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ).
REPAIR open circuits.
free wiring diagrams at www.bbbind.com
×