Engine V6 01 Stang, P1285,P1299,P1289. HELP!

3

38lv3stang

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Apr 3, 2018

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Apr 3, 2018

#1

• Apr 3, 2018

• #1

Hey. I just bought this 2001 Mustang with the 3.8L V6.
I got 3 codes. P1299, P1285, P1289.
I flushed my coolant refilled and burped.
I changed my CHT, ECT, checked my ECT wires. And still have the problem.
I can rest the codes and drive it for 5 mins or till it warms up and the my temp gauge will stop working and the car will go into limp mode.
But as long as it is cold it runs great. I NEED HELP.
I dont know where to go from here or what I can do next. Thanks.

 

wmburns

SN Certified Technician

Aug 14, 2009

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Apr 3, 2018

#2

• Apr 3, 2018

• #2

Are you positive that all of the air has been removed from the motor?

V6 coolant refilling procedure
http://www.allfordmustangs.com/foru...stang-irregular-rpms-showing-hot.html#2604913

If this were my car I would rule out a wiring and/or connector problem to the CHT itself. Perhaps a short between the 5 volt reference and the signal return line or an open between the CHT and PCM.

>>
P1289 - Cylinder Head Temperature (CHT) Sensor Circuit High Input
Open circuit in CHT harness
Damaged CHT sensor
Improper harness connection
Damaged PCM

 

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38lv3stang

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Apr 3, 2018

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Apr 3, 2018

#3

• Apr 3, 2018

• #3

How would I test if there was a short or not.
My temp gauge is all over the place to. It is in the middle then red lined then nothing.
And I followed a
Chiltons way to burp it, so pretty sure there is no air.

 

wmburns

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Aug 14, 2009

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Apr 3, 2018

#4

• Apr 3, 2018

• #4

In the interest of covering the "basics" it would be wise to perform a through check of the charging system.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

The fact that the dash temperature gauge is "all over the place" all but "proves" the signal return from the CHT is unstable. Since the CHT sensor is new it's seems more likely to me there's a problem in the wiring or connector.

One method to trouble shoot this "issue" is to perform a "wiggle test" while watching the dash temperature gauge.

Another method is to monitor the CHT PID with an ODB2 scanner. Here's some information on an affordable Windows based unit.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

 

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38lv3stang

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Apr 3, 2018

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Apr 4, 2018

#5

• Apr 4, 2018

• #5

I have a ODB2 scanner. What should I watch for as I am monitoring the CHT PID. Whats normal and whats not.

 

wmburns

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Aug 14, 2009

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Apr 4, 2018

#6

• Apr 4, 2018

• #6

If you think about it what you are looking for is a change when wiggled.

Or if you need a value then make note of the CHT when the dash gauge is in the normal range.

Bottom line is the change is going to be large as the connection comes and goes.

 

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38lv3stang

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Apr 3, 2018

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Apr 4, 2018

#7

• Apr 4, 2018

• #7

So just tested, before i started the car ect temp was -40. thats a system of bad ect sensor.Right???????
Then started the car and temp gauge worked then failed. So....

 

wmburns

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Aug 14, 2009

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Apr 5, 2018

#8

• Apr 5, 2018

• #8

38lv3stang said:

So just tested, before i started the car ect temp was -40. thats a system of bad ect sensor.Right??????

Click to expand...

No! Not necessarily. -40 really only means the lowest reading possible. But often that can mean an open signal return line.

But didn't you state the CHT sensor was changed? What are the chances of there being two bad CHT sensors? IMO you should be expanding the possible "causes".

Especially since the full confirmation tests documented in pinpoint test DA haven't been done. These test would rule out:

• Short to ground
• short to VPWR
• incorrect VREF 5 volt reference.
• Open (signal return or VREF)

If you are interested in getting a full copy of the Ford factory service manual with wiring diagrams I maybe able to help. PM if interested.

OBTW, a 2001+ V6 Mustang does not have an ECT sensor. Only a CHT is used.

 

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38lv3stang

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Apr 3, 2018

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Apr 6, 2018

#9

• Apr 6, 2018

• #9

I changed the CHT, still have the problem. Im thinking wiring between Cht and PCM.