Code 452
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Freshman User
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Yes. I plugged the ABS module back in, Rear ABS light is back on, truck running , all lighting in the truck works as it should. Unplug it, Rear ABS light goes out, all lighting works fine, no change in trans. Is there a way to positively test the torque converter or the trans internals to completely eliminate them from suspicion? I am getting very close to getting a stand alone shift controller for this thing and want to be %100 on the trans and TC before I drop that cash.
Senior User
Joined: Feb 2019
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OK. We pretty much know what it isn't. with ABS module unplugged there should be no light anytime. These are a very poor designed ABS system. There are several easy tests for the internal works of the trans. They are posted in this forum in several places. The torque conv. and clutch packs can be tested without removal. Maybe someone who reads this post can direct you to these. I know this gets to be a PITA, but i went thru the same ordeal. Be patient, or for around $2000 dollars replace it. I replaced everything on mine, including the lugnuts, and found no cure. Good luck!
Lead Driver
Joined: Jan 2019
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From: N.W. Alabama
may, may not help, but onefifty94 tested his post #16 starts it
Code 629 E40d Back to Square 1
Help Please - Page 2 - Ford Truck Enthusiasts Forums
Code 629 E40d Back to Square 1
Help Please - Page 2 - Ford Truck Enthusiasts Forums
Senior User
Joined: Feb 2019
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All you will need is a line pressure guage. The rest can be done from the drivers seat, Multi meter tests can be done later. We are testing the hard parts in the transmission first. Tractor supply has a 400psi guage for around $6.00.
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Fleet Owner
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From: Easton,Ks
It is not the transmission as the yellow ABS lamp is on.
A breakout box will not help you unless you use it to see the wave form on the wire from the PSOM to the PCM.
But we know that the wave form from the PSOM to the PCM is bad.
The problem would be between the RABS module/PSOM and the rear end (maybe bad wiring).
Could be bad bearings or bad tone ring in the rear also.
This is why the wave form needs to be checked on the input to the PSOM.
Anstand alone shift controller will not help the yellow lamp for the RABS.
Attachment 281981
Attachment 281982
Attachment 277289
Attachment 277292
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A breakout box will not help you unless you use it to see the wave form on the wire from the PSOM to the PCM.
But we know that the wave form from the PSOM to the PCM is bad.
The problem would be between the RABS module/PSOM and the rear end (maybe bad wiring).
Could be bad bearings or bad tone ring in the rear also.
This is why the wave form needs to be checked on the input to the PSOM.
Anstand alone shift controller will not help the yellow lamp for the RABS.
Attachment 281981
Attachment 281982
Attachment 277289
Attachment 277292
/
Senior User
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Apparently i am failing to understand this issue. Are we not checking to see if transmission is sound. Regardless of code 452, we need to know this. This test is not related to anything electronic. Valve switching is all manual. If transmission is faulty, nothing will fix it, especially a seperate controller.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
When you get a code 452 you do not look at the transmission.
The PCM says it is not getting speed information from the PSOM so it ups the transmission pressure and this higher pressure causes the hard shifts.
Continuous Memory DTC 452 indicates the PCM detected an error in the PSOM output signal during the last 40 warm-up cycles.
Possible Causes:
-- Damaged Rear Anti-Lock Brake Sensor.
-- Damaged PSOM.
-- Damaged harness circuits.
-- Damaged Powertrain Control Module (PCM).
The PCM says it is not getting speed information from the PSOM so it ups the transmission pressure and this higher pressure causes the hard shifts.
Continuous Memory DTC 452 indicates the PCM detected an error in the PSOM output signal during the last 40 warm-up cycles.
Possible Causes:
-- Damaged Rear Anti-Lock Brake Sensor.
-- Damaged PSOM.
-- Damaged harness circuits.
-- Damaged Powertrain Control Module (PCM).
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Freshman User
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I have a new Motorcraft VSS installed and changed the fluid in the diff and performed a visual on the tone ring with the rear wheels off the ground. It looked fine, no nicks or bad teeth all the way around. I did not check the clearance on the sensor though. The installation seems straightforward so by design the sensor would have to be in the right place if it was properly seated in the hole and bolted down, which it is. I ohmed it out at the sensor, at the back of the PSOM, and at the plug that’s under the hood near the DIagnostic plug. They all have 1400. Can I hook my meter up to that plug and take it for a spin and see if I get some sort of reading to see if the sensor is reading the tone ring properly? I also would be interested to test the trans just to eliminate any other possibilities outside of this code 452 and shifting. Where do I install the gauge and do the test?
Fleet Owner
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From: Easton,Ks
You might want also unplug the Speed Control module to see if it is causing the 452 and hard shifting.
As far as putting a pressure gauge on the test port we know the the pressure will be very high with the 452 code and hard shifting.
As far as putting a pressure gauge on the test port we know the the pressure will be very high with the 452 code and hard shifting.