DL20 DTC P0117: SIMULATE OPPOSITE SIGNAL TO PCM
Disconnect CHT sensor.
Connect scan tool.
Key on.
Access CHT V PID.
Is the CHT V PID more than 4.6 volts?
Yes No
REPLACE CHT sensor. For LS6/LS8 and Thunderbird with Electronic Throttle Control: GO to DL22 .

All Others: GO to DL21 .




DL21 CHECK VREF CIRCUIT VOLTAGE AT TP SENSOR
Disconnect throttle position (TP) sensor.
Note: GO to Pinpoint Test DH and refer to Pinpoint Test Schematics and Connectors for TP harness connector pin-out information.

Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the TP sensor harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
There is sufficient VREF voltage. RECONNECT TP sensor. GO to DL22 . KEY OFF. GO to C1 .




DL22 CHECK CHT SIGNAL CIRCUIT FOR SHORT TO GROUND
Note: IMPORTANT Marauder Only - See pinpoint introduction for ECT\CHT information.

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.
Is each resistance greater than 10,000 ohms?
Yes No
REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPAIR short circuit.




DL30 DTC P1285: EARLY WARNING OF ENGINE OVERHEAT CONDITION
An engine overheat condition was sensed by the CHT sensor.

Check cooling system for:
Correct coolant level.
Internal or external coolant leaks.
Blockage of radiator.
Cooling fan operation.
WARNING: TO AVOID PERSONAL INJURY, DO NOT UNSCREW THE COOLANT PRESSURE RELIEF CAP WHILE THE ENGINE IS OPERATING OR HOT. THE COOLING SYSTEM IS UNDER PRESSURE; STEAM AND HOT LIQUID CAN COME OUT FORCEFULLY WHEN THE CAP IS LOOSENED SLIGHTLY.

Note: If electric cooling fan does not operate, return to Section 3 for electric cooling fan DTC or symptom diagnosis.

Is cooling system OK?
Yes No
CHECK CHT sensor operation. GO to DL3 . REPAIR as necessary. REFER to Engine Cooling, Section 303 in the Workshop Manual for symptom diagnosis of Engine Overheats or Loss of Coolant.

 

DL40 ENGINE TEMPERATURE WARNING INDICATOR LAMP ON OR TEMPERATURE GAUGE INDICATES HOT, BUT ENGINE IS NOT OVERHEATING
Note: PCM Quick Test must be performed prior to entering this Pinpoint Test.

Was PCM Quick Test performed prior to entering this Pinpoint Test?
Yes No
No Diagnostic Trouble Codes (DTCs) received during PCM Quick Test. GO to DL41 . GO to Section 3 and RERUN Quick Test. REPAIR any DTCs as necessary.




DL41 ENGINE TEMPERATURE INDICATOR LAMP ON OR TEMPERATURE GAUGE INDICATES HOT, WITH NO DTCs
The Engine Temperature Warning Indicator (gauge or lamp) is a warning system that gives the driver information during an engine overheating condition. The PCM monitors the CHT sensor and determines if fail-safe cooling mode is needed. If fail-safe cooling is needed, the PCM can signal the driver in two ways:

Temperature Warning Indicator hard wired to PCM:

PCM grounds the engine temperature warning circuit when the engine is overheating. This causes the instrument cluster indicator to illuminate and/or forces the temperature gauge to H (hot) zone. A P1285 will also be stored in the PCM.

Temperature Warning Indicator information received through SCP:

PCM sends a SCP message to the instrument cluster to signal an overheating condition. This causes the instrument cluster indicator to illuminate and/or forces the temperature gauge to H (hot) zone. A P1285 will also be stored in the PCM.

This test ONLY diagnoses the PCM hard wire systems with no PCM DTCs.

For any other type of Engine Temperature Warning Indicator system problems, refer to Workshop manual for diagnosis procedure.

Possible causes:

Damaged engine coolant temperature sensor.
Instrument cluster concern.
Wiring harness fault between PCM and Instrument cluster. (PCM output pins: 42 for gauge or 45 for lamp.)
Damaged PCM.
Disconnect PCM.
Key on.
Is the engine temperature warning indicator lamp OFF and the temperature gauge in the normal zone with the PCM disconnected?
Yes No
Key off. REPLACE the PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). The PCM has not attempted to ground the Engine Temperature Warning circuit and turn the engine temperature indicator lamp ON or force the temperature gauge to the H (hot) zone. REFER to Instrument Cluster, Section 413 in the Workshop Manual for further diagnosis.

DL80 P0116: CHECK TEMPERATURE SENSOR RESISTANCE WITH ENGINE OFF
Note: IMPORTANT Marauder Only - See pinpoint introduction for ECT\CHT information.

Note: Verify that engine temperature is at ambient room temperature before continuing with this test. A soak period of 6 hours may be required. Refer to Diagnostic Trouble Code (DTC) Descriptions , in Section 4 for information concerning P0116.

Key on, engine off.
Disconnect CHT sensor.
Measure CHT sensor resistance. Refer to the chart at the beginning of this Pinpoint Test for resistance specifications.
Is resistance within specification?
Yes No
GO to DL81 . REPLACE suspect sensor.



DL81 P0116: CHECK TEMPERATURE SENSOR RESISTANCE WITH ENGINE RUNNING
Note: Verify that engine is at operating temperature before taking readings.

Run engine for two minutes at 2000 rpm.
Measure temperature sensor resistance. Refer to the chart at the beginning of this Pinpoint Test for resistance specifications.
Is resistance within specification?
Yes No
Fault is not present at this time. COMPLETE OBDII Drive Cycle to determine if Fuel, HEGO, Catalyst and Misfire monitors can be executed (REFER to Section 2, Drive Cycles ). Retest if necessary. REPLACE suspect sensor.



DL90 DTCS P0117, P0118, P1117, P1289 OR P1290: INTERMITTENT CHECK
Note: IMPORTANT Marauder Only - See pinpoint introduction for ECT\CHT information.

Connect scan tool.
Key on.
Access CHT V PID.
While observing the PID, complete the following:
Tap on the sensor to simulate road shock.
Wiggle the sensor connector.
Is there any large changes in the voltage reading?
Yes No
Key off. DISCONNECT and INSPECT connectors. If OK, REPLACE sensor. COMPLETE OBDII Drive Cycle to verify repair (REFER to Section 2, Drive Cycles ). GO to DL91 .



DL91 CHECK ELECTRONIC ENGINE CONTROL (EC) WIRING HARNESS
Again access CHT V PID.
While observing the PID, complete the following:
Hold the vehicle harness close to the sensor connector. Wiggle, shake and bend small sections of wiring harness while working toward the PCM.
Is there any changes in the voltage reading?
Yes No
ISOLATE fault. REPAIR as necessary. COMPLETE OBDII Drive Cycle to verify repair (REFER to Section 2, Drive Cycles ). GO to DL92 .

 

DL92 CHECK PCM AND VEHICLE HARNESS CONNECTOR
Disconnect PCM.
Disconnect temperature sensor.
Are connectors and terminals OK?
Yes No
Fault is not present at this time. COMPLETE OBDII Drive Cycle (REFER to Section 2, Drive Cycles ). REPAIR as necessary. COMPLETE OBDII Drive Cycle to verify repair (REFER to Section 2, Drive Cycles ).




DL100 DTC P1299 OR P0217 INDICATES AN ENGINE OVERHEAT CONDITION OCCURRED
Note: Refer to Section 4 , Diagnostic Trouble Code (DTC) Description for possible causes and additional DTC description information.

WARNING: TO AVOID PERSONAL INJURY, DO NOT UNSCREW THE COOLANT PRESSURE RELIEF CAP WHILE THE ENGINE IS OPERATING OR HOT. THE COOLING SYSTEM IS UNDER PRESSURE; STEAM AND HOT LIQUID CAN COME OUT FORCEFULLY WHEN THE CAP IS LOOSENED SLIGHTLY.

Check engine coolant level.
Is the engine coolant level fill correct?
Yes No
REFER to Engine Cooling, Section 303 in the Workshop Manual for symptom, Engine Overheats. REFER to Engine Cooling, Section 303 in the Workshop Manual for symptom, Loss of Engine Coolant.




DL110 DTC P0125, P0128: CHECK ENGINE COOLANT LEVEL
Diagnostic Trouble Code (DTC) P0125 or P0128 indicates the engine coolant temperature has not achieved the required engine operating temperature level, since engine start-up within a specified amount of time.

Possible causes:

Insufficient warm up time.
Leaky or stuck open thermostat.
Low engine coolant level.
Malfunctioning CHT sensor.
Malfunctioning ECT sensor (Marauder Only).
WARNING: TO AVOID PERSONAL INJURY, DO NOT UNSCREW THE COOLANT PRESSURE RELIEF CAP WHILE THE ENGINE IS OPERATING OR HOT. THE COOLING SYSTEM IS UNDER PRESSURE; STEAM AND HOT LIQUID CAN COME OUT FORCEFULLY WHEN THE CAP IS LOOSENED SLIGHTLY.

Check engine coolant level.
Is the engine coolant level fill correct?
Yes No
GO to Engine Cooling, Section 303 in the Workshop Manual for further diagnostics. FILL engine coolant to proper level. Complete Comprehensive Component Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles).





(whew that was long) Good luck

 

You do know that you can overheat with NO thermostat - the coolant can flow through the radiator too fast to get cooled without some restriction........

 

highly doubt that is possible, the coolant itself is a restriction. The coolant can only move as fast as the water pump turns. No thermostat the engine should be overcooling.

 

So go buy a Chevy.......

 

Have you checked the water pump as suggested?

.

 

Sorry, Patrick - we used to see that in the "old days". Yes, at low RPM's it will generally overcool, but at high RPM's it can undercool. Of course, this assumes a good water pump and no other restrictions in the system such as a clogged radiator.

 

I totally appreciate all the info you've put up. I just bought the scanner after having trouble with the truck. Can I troubleshoot with it and not just read and reset codes? Been so busy trying things I have not had time to check the manual that came with it. I did find out more info today. I did the combustion gas leak test and it showed negative. I ran it for longer than speced and used my vacuum tester instaed of that wimpy squeeze ball. I feel I got a through test and have no leakage. I also discovered that if I do not run the A/C, it does not go into overheat condition. If I run the A/C, after I park it and turn it off, it will go in to the overheat. When I realized that I remembered I did not have the over heat symptoms until I repaired the A/C control unit. One of those "set it and forget" type thingys. If anyone wants to e-mail directly my address is taffrail@tx.rr.com

 

Do you mean have I ran an analysis to determine exactly how many parts per million (or billion or each) of anti freeze are in my theoretical cooling system, the response to that interrogatory would be in the affirmative. Not my first car, truck, or century for that matter. Means I'm over 50 and changed head gaskets before a lot of you were born. Sorry...got carried away. Actually got to ride in my truck tonight. It was great.

 

And that would be fun how?

 

No. I mean did you test the water pump. The impellers are known to corrode/rust to the point of not flowing enough volume of coolant.

Let me just share this with you. One of my sons and I have a running joke. Every time we notice an idiot we tell the other 50% then point. This comes from the fact that most institutions today do not look at the grades people have and some times have to settle for the individual who passed the test but only by the required amount. In most cases that is 50%. That effectively means that he only knows 1/2 of the subject matter.

Now having shared this with you I don't want you to think that I believe that you are an idiot. Far from that. We only want to help you fix your fine truck. We are only giving suggestions as to what to check. All of us do this for free. A thank you for the effort is welcome but not necessary. Snide remarks are not welcome and are often rejected and replied to with insults, badgering, name calling.....
I will not lower myself to this level. I will however no longer offer assistance until it is confirmed that said water pump was tested.

Respectfully

Jean Marc Chartier

 

How many miles are on the truck agian? From the sound of it, seems like you might not be getting enough air flow across the radiator and condenser together. The radiator is able to cool enough as is but once the condenser is pumping hot air into the radiator, the cooling system can't keep up. Which would tell me you have either a bad w/p or a bad fan clutch or both. Ive got a take off fan (about 30k on it) you could borrow if you'd like to pop it on there, as well as the necessary fan removal tools.

 

Well JMC I owe you an apology. You wrote well, I read wrong and gave you the wrong answer. I am going to do a flush tomorrow and in preparation of that I drained the system and flush it will cold water after it cooled for 4 hours. I took the upper hose lose to assist in that as there is no thermostat in there at the moment. While I had it loose, I started the engine very briefly. It was not the blast I expected but it did shot a nice volume of water about 2 feet. Is that any indication at all of the pump condition. It is not leaking and to be honest, looks new. Speaking of which, which way is the fan mounted?

 

Apology accepted. We are all here because of our common interest in Ford trucks. Now back to your problem. If he water pump flows then we can eliminate that. If there is no coolant loss then then the system may not actually be overheating. Can you measure the temperature at the radiator? If the PCM is in fact receiving a false reading from the CHT then the sensor may be defective or the wires are shorting out and causing a false reading. Unfortunately access to the sensor requires removing the Intake manifold. Fortunately the CHT signal to the PCM can be monitored from your instrument cluster. On a cold engine press and hold the trip meter reset button and turn the key to on. Hold the button till test appears in the odometer display then release. The system will test out and the word GAUGE will appear and the gauges will sweep. Press and release the button till dE6C0?? appears. The 0?? represents the current temperature in degrees Celsius. As the engine is cold it should read the outside temperature +or- a few degrees. If it doesn't then the sensor or the wiring is the culprit. Start the engine and monitor the temperature. On an engine at operating temp it should read between 80 and 95 degrees C. Remember this is Celsius.

.