Can't Communicate with ABS module
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 1
Likes: 1
From: Northern Alberta
Can't Communicate with ABS module
Hi everyone, this is my first time posting on here but I am a long time enjoyer of the forums. I am having trouble with my parents 2012 f150 lariat 5.0. I can't communicate with the abs module at all but I will start from the beginning with all that I have done so bare with me.
My parents recently purchased this truck and the previous owner had said that the abs module was constantly running even when the key was off so they pulled the 60 amp fuse that is in the fuse box under the hood. So we bought another abd module from a wrecker that is apparently a working unit. It is a Cl-34 which is the same one that was on the truck.
I'm new to using forscan but what I gathered from the internet is that I connect to the truck with my laptop and then I would be able to save the profile of the old abs module and the flash it to the new one. But when I hooked up my laptop I got several DTCs that all revolve around no communication with the abs module. DTC U0121 is the code to be exact. The abs doesn't even show up as a module. Well, I thought it must just be because of the bad module so I also learned I could look up the As-built data from Ford and program the new module that way so I wasn't too worried.
I began the process of changing the module out which I have never done before but it went not too badly. But again when I was all done and I hooked up my laptop I was met with the same trouble codes after I had even cleared them. I thought okay, maybe I just have to clear the codes and try again, No luck, can't even see abs listed as a module but now I have no U0121 codes at all.
Well I thought my 2nd hand abs module must be bad but my parents have another 2012 f150 5.0 so I went and unplugged the abs connector from the truck and plugged in my 2nd hand module and then booted up forscan and I can see the abs module. I can see the service bleed procedure as well as an advancetrac test as well. Surely that must mean the 2nd hand module is good?
Then I assume I must have a broken wire/connection on the truck side of things but I went through the AllData pinpoint test B and tested the powers. grounds, and ohms on the canbus wires to the obdII port and it passed every test.
Forgot to mention that I also checked all 3 fuses that have to do with the ABS system and they are all good.
So I am at a loss of what the issue could be. Does anyone have any idea of what I could do? Is it possible the new abs module is bad even though I can communicate with it when I hook it up to another truck?
My parents recently purchased this truck and the previous owner had said that the abs module was constantly running even when the key was off so they pulled the 60 amp fuse that is in the fuse box under the hood. So we bought another abd module from a wrecker that is apparently a working unit. It is a Cl-34 which is the same one that was on the truck.
I'm new to using forscan but what I gathered from the internet is that I connect to the truck with my laptop and then I would be able to save the profile of the old abs module and the flash it to the new one. But when I hooked up my laptop I got several DTCs that all revolve around no communication with the abs module. DTC U0121 is the code to be exact. The abs doesn't even show up as a module. Well, I thought it must just be because of the bad module so I also learned I could look up the As-built data from Ford and program the new module that way so I wasn't too worried.
I began the process of changing the module out which I have never done before but it went not too badly. But again when I was all done and I hooked up my laptop I was met with the same trouble codes after I had even cleared them. I thought okay, maybe I just have to clear the codes and try again, No luck, can't even see abs listed as a module but now I have no U0121 codes at all.
Well I thought my 2nd hand abs module must be bad but my parents have another 2012 f150 5.0 so I went and unplugged the abs connector from the truck and plugged in my 2nd hand module and then booted up forscan and I can see the abs module. I can see the service bleed procedure as well as an advancetrac test as well. Surely that must mean the 2nd hand module is good?
Then I assume I must have a broken wire/connection on the truck side of things but I went through the AllData pinpoint test B and tested the powers. grounds, and ohms on the canbus wires to the obdII port and it passed every test.
Forgot to mention that I also checked all 3 fuses that have to do with the ABS system and they are all good.
So I am at a loss of what the issue could be. Does anyone have any idea of what I could do? Is it possible the new abs module is bad even though I can communicate with it when I hook it up to another truck?
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
You should put ALL your truck's details & history (as much as you know) into your signature so it shows with each post, as this page explains:
(click this text)
Phone apps don't always show signatures, so you may need to switch to a real browser in desktop mode on your phone, or just use a desktop/laptop computer. Put your location (nearest city) in your profile &/or signature, & upload an avatar of the truck. The more pics you post (NOT in your sig) of the truck, engine, wiring, labels, & undercarriage, the more likely we can help you. Not all its details are relevant to these issues, but you don't necessarily know which ones are relevant, so just put everything in now.
"All" tells us nothing. We don't know if YOU know what "all" the wires needed for ABS communication are. So if you want help, you need to LIST each one that you checked, and describe exactly how you checked it. Same for "all" (EACH of the) fuses.Pics of the process would help, including the equipment you're using, and what settings you're using on each tool. If you have AllData, post screenshots of the wiring diagrams you used, and good, clear, focused, well-lit pics of the connectors on your truck so we can confirm the wire colors match the diagrams', and that you're probing the correct wires.
(click this text)
Phone apps don't always show signatures, so you may need to switch to a real browser in desktop mode on your phone, or just use a desktop/laptop computer. Put your location (nearest city) in your profile &/or signature, & upload an avatar of the truck. The more pics you post (NOT in your sig) of the truck, engine, wiring, labels, & undercarriage, the more likely we can help you. Not all its details are relevant to these issues, but you don't necessarily know which ones are relevant, so just put everything in now.
"All" tells us nothing. We don't know if YOU know what "all" the wires needed for ABS communication are. So if you want help, you need to LIST each one that you checked, and describe exactly how you checked it. Same for "all" (EACH of the) fuses.Pics of the process would help, including the equipment you're using, and what settings you're using on each tool. If you have AllData, post screenshots of the wiring diagrams you used, and good, clear, focused, well-lit pics of the connectors on your truck so we can confirm the wire colors match the diagrams', and that you're probing the correct wires.
Senior Member
Joined: Nov 2017
Posts: 6,637
Likes: 1,292
From: Washington
Nothing wrong with trying to learn new things but you jumped way ahead of normal troubleshooting protocol. Diving in to Forscan module programming based on what somebody said might be a "constantly running ABS module".
Go back to the basics. Is the SES/CEL light on? Is there a code, or codes? What are they?
There must be some youtube videos out there about how to check the CAN wires based on voltage or resistance measurements because all of a sudden many people are posting about checking them like that. But the data is digital.
https://en.wikipedia.org/wiki/CAN_bus
Go back to the basics. Is the SES/CEL light on? Is there a code, or codes? What are they?
There must be some youtube videos out there about how to check the CAN wires based on voltage or resistance measurements because all of a sudden many people are posting about checking them like that. But the data is digital.
https://en.wikipedia.org/wiki/CAN_bus
Junior Member
Joined: Jul 2024
Posts: 1
Likes: 0
I know this is an old post, But I am having the same issue. FORScan doesn't even show the used ABS but I have the U0121 code "Can't communicate with ABS" . Would you share with me if you found the issue and what it was please? I have done everything that i know to do without success. Thank you, I really appreciate your reply.
