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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 23821
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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I have 2009 f 150 lariat idle rough and no respond to throttle.I

Customer Question

Hi,I have 2009 f 150 lariat idle rough and no respond to throttle.I have 2 codes-PO60A,UO300
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Ford. The Ford Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: The PCM and throttle body was replaced at dealer 5 month ago
JA: Are you hoping to fix this yourself?
Customer: yes
JA: Great! What have you tried so far?
Customer: replaced all injectors,replace fuel pump,fix broken wire at evap canister valve
JA: Is there anything else the Ford Mechanic should be aware of about your Ford?
Customer: 298 000 km
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Ford Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Ford
Expert:  Adam Legler replied 1 year ago.
Hello, my name is ***** ***** I am an ASE Master and Advanced Level Certified Automotive Repair Technician with over 12 years experience and I've personally worked on over 25,000 vehicles. I also carry the Service Consultant and Parts Specialist certifications. I see you have a question about your F150 and I can help you!First, I'd like to ask a question, then we can get into more detailsWhich engine do you have in the truck? With me and this process, please always feel free to ask any questions that come to mind. It is my goal to determine the cause and remedy for your concern. I look forward to a speedy repair! Thank you.
Customer: replied 1 year ago.
5.4 triton
Expert:  Adam Legler replied 1 year ago.
Nice, thank you. Great motor too!Your question caught my eye because I remember your exact concern on a clients vehicle I worked on a couple years back. I kept a flat rate journal of every vehicle I worked on and I going back thru it to see what the story was. Regardless, I'll give you a list of basic things to check here in one moment. Thank you!
Customer: replied 1 year ago.
I was told that if I have the wrench tool on my dash it is something mechanical????Is it normal when you disconnect VCT the I get my dash flashing the security lock and lost communication with PCM?
Expert:  Adam Legler replied 1 year ago.
Thanks for you patience I'm still writing my prelim. The Ford "wrench" lamp simply denotes a CEL issues that has put the vehicle into an active limp mode.If you disconnect any part of the VCT (Variable Camshaft Timing) system, the security lamp should never begin to flash or lose comm with the PCM. I bet this may all be part of the issue you described in detail up top, I'd like to focus there first and lets see what else the fix will take care of.
Customer: replied 1 year ago.
I had friend to hook his laptop to vehicle and after he did pressure test on all cylinders all codes were gone and truck ran for 80 km,than I park the truck at home.In morning when I start up the vehicle everything was back in limp mode????
Expert:  Adam Legler replied 1 year ago.
Thanks for your patience. When looking up the theory and operational conditions of this code there is a massive variety of issues that can cause it, 90% of which do require some type of factory level scan tool or a Ford IDS. Your concern makes sense, this code has to do with the PCM believing there is some kind of internal control module fault. Here's where I'd like to start. The U0300 is a communication code having to do with a logic error between the PCM and the instrument cluster. Now the IPC (Instrument Panel Cluster) is the main logic center for the Ford PATS, which is your built in factory theft system.When this issues happens, do you noticing anything happening with your gauges? Other than the wrench lamp illuminating?
Customer: replied 1 year ago.
Not 100% sure maybe gauge for transmission fluid temperature
Expert:  Adam Legler replied 1 year ago.
That's OK, no worriesDo you feel comfortable and/or do you have the necessary tools to do some pinpoint wire testing? What I'd like to do is test the power and grounds to the pcm at terminal 67 and 68 from fuse 75. This will require something to pierce the wiring, since the testing will have to be done with the vehicle in its operational condition, and we will also need a very good Digital Multi-meter. To make things more complicated (sorry) this testing will have to be done while the vehicle is actually malfunctioning. If we do this testing while the vehicle is running fine, then what would potentially be a bad reading may come back as ok, and we will have overlooked the issue.Please let me know if you have any questions for me prior to proceeding. Since there is specific testing involved I'd like to know you're comfortable with the above steps and tools necessary for accurate diagnosis. If so I will lay out the procedures, include visuals and you can report back your findings.
Customer: replied 1 year ago.
Yes,I think i can do it if I know the procedures
Expert:  Adam Legler replied 1 year ago.
Ok, I'm glad you're comfortable with that. I'm sure you understand why I have to ask.I've actually thought of one more thing to try prior to getting into some ckt testing. I'd like to switch out the PCM's power relay with another one. A lot of relays are the same across all makes and models of US manufacturers. See the attached diagram of the underhood fuse box. Note the location of the PCM power relay in the upper left corner of the diagram. Id like you to pull it out and swap it with one of the other identical relays next to it. Preferably not the starter, but the blower motor relay will be OK to remove temporarily for testing. When you have that PCM relay out, I'd like you to visually check for any signs of corrosion. It can be in the form of oxidation, calcium, lime, etc... This is very common in humid areas or areas that experience a lot of moisture. If you're unsure, feel free to take a picture and attach it to this conversation.
Expert:  Adam Legler replied 1 year ago.
Ok, now see the attachment, my apologies
Customer: replied 1 year ago.
remove the relay no oxidation ,calcium,lime at all ,swap relay with blower motor relay
Expert:  Adam Legler replied 1 year ago.
Yep, you got it. Go ahead and swap them. Now this may take a little time to prove if this will make a difference, since in your description it sounded like the concern did have some tendency to be intermittent.
Customer: replied 1 year ago.
no change ,running rough,no respond to throttle same codes
Expert:  Adam Legler replied 1 year ago.
ok then, onto circuit testing. Just so you know, I do abbreviate circuit as CKT. Give me a moment while I finish writing out our first steps
Customer: replied 1 year ago.
OK ,thank you
Expert:  Adam Legler replied 1 year ago.
First, I want to check power to the pcm at terminals 67 and 68. This power is supplied from fuse 75 via the PCM power relay. Specifically, I want the voltage reading while cranking the engine over, and right after the vehicle starts.So on the PCM, you will notice 3 connectors. The PCM is located at the right rear of the engine compartment, see picture, the 3 connectors are circled in red.We will be connector C175B, which is located closest to the passenger side.I've attached 2 additional pictures. One is of the connector itself, the next is a description of the circuits. 67 and 68 are yellow and grey wires.You may need to pull back some of the wire sheathing to access the wires. Note, there will be a lot of wires, also other wires do share the same colors. We can do one wire at a time, we want to gently pierce one of the wires and hook up our DMM. Make sure that whatever you pierce the wires with, whether it be a piercer, or a t-needle, make sure the bare metal comes in contact with nothing around it, we don't want to short power to the PCM. Again, let me know if any of this is unclear, I'll be happy to clarify. Also, remember the vehicle needs to be running in its problem state.
Customer: replied 1 year ago.
I receive picture of the connector C175B,no pictures of connector itself with description
Customer: replied 1 year ago.
Can you send them to me please
Expert:  Adam Legler replied 1 year ago.
Sorry about that, sometimes I get a little ahead of myself when it comes to file attachments.
Expert:  Adam Legler replied 1 year ago.
Or maybe not, It didn't send them that time either
Expert:  Adam Legler replied 1 year ago.
3rd times the charm...
Expert:  Adam Legler replied 1 year ago.
Hello again, just wanted to let you know I'll be off the rest of the afternoon There is no rush at all, so please reply once you've completed your test, I can access my interface via mobile. Thanks again and I look forward to the results
Customer: replied 1 year ago.
Hi,sorry my volt meter did not work,I got new one I disconnect the battery before I went to store,when I got back I install the ground to battery and remove the plug to PCM to located the 2 wires and when I start the vehicle it start running ok again.Maybe because i move with wiring or because the battery was disconnected not sure but now I can not do any more testing if its running Ok or can I do more tests?The voltage on both wires is 14.45V when vehicle is running.When vehicle is off voltage is 0 on both wires.
Expert:  Adam Legler replied 1 year ago.
Hmm, that is interesting. The answer to your questions is no, we can't do anymore testing until the vehicle begins malfunctioning again. Even though it wasn't in the directions, when you removed that PCM connector did you notice any scale, or calcium, lime, oxidation on the connector? Also was the connector whole, meaning the clips (handle like devices) that kept it secured into the PCM intact?Funny thing, you may have inadvertently performed the next step I was going to suggest to you, which is what we call a hard reset of the pcm which can be done one of two ways. First is disconnecting the battery overnight, second is to completely unplug the PCM overnight. We say overnight because the PCM contains capacitors, which can help the computers and modules in the vehicle retain memory in the event of a power loss.
Expert:  Adam Legler replied 1 year ago.
Also, when the PCM was replaced at the dealer 5 months ago, was it for this issue?
Customer: replied 1 year ago.
There was no calcium,lime,on connector clips where secured to PCM,the PCM was replaced for same reasons
Expert:  Adam Legler replied 1 year ago.
That's a really good thing, thanks for checking!Ok, so here's the instance I had almost 2 years ago to the day:Client came in with your same codes, having in fact had the PCM replaced the year prior. I was working with a Ford master tech at the time, and he helped me diagnose it (I know because I gave him half of my flagged diagnosis). Anyways when you look up Ford's diagnostic tree for the concern, other than listing what you already tested and have done above with me, they want the PCM programming changed. In my instance, this worked, client never returned with the same issue again. I had a Ford IDS at the time, and this was a simple procedure. In your case though, it may involve taking it to the dealer or an independent shop that has the Ford IDS. You will still be in the warranty period for the work they performed 5 months ago however, so it may be worth mentioning to them that you're having the SAME issue that they corrected 5 months ago. The ONLY other issue could be the MAF sensor (Mass air flow). This sensor sits in the air cleaner housing and tells the engines computer how much air is entering the intake so it knows how much fuel to mix with it. The description of a MAF sensor failure is almost exactly what you described, BUT I didn't bring that up until this point, only because when they typically malfunction they also come up with a p061b code, which you don't have. If you like I can type up the diag steps for that MAF sensor and we can go over them. But if that checks out, and everything else checks out, you know like your battery connections and battery condition, making sure no aftermarket fuel or performance tuners/programs have been installed, etc... Then the next step would be to return to the dealer for warranty work from your previous repair ONLY if your concern returns, you may have corrected it with the reset of the PCM.
Customer: replied 1 year ago.
What is the procedure to check the MAF sensor?
Expert:  Adam Legler replied 1 year ago.
You bet! One thing though before we start with that. Using your new DMM, make sure that battery voltage does not drop below 9 volts while cranking.MAF check-out:Disconnect the Mass Air Flow (MAF) sensor connector. It will be a small 5-6pin connector on the air box. Recheck to see if the engine will then start and idle without stalling.If the engine idles without stalling after having disconnected the MAF sensor, this suggests that the MAF sensor input to the PCM is low either due to the cause of sensing element contamination, failure, or an air induction issue of the inlet tube or air filter element. I would suggest cleaning the MAF sensing element, however this is very sensitive and can only be cleaned with actual MAF sensor cleaner.note! You will set another fault code that may have to be cleared upon plugging the MAF sensor back in.If the issue remains after disconnecting the MAF sensor and starting the vehicle, the next step is to check for potential of electrical interference such as what may be produced from the alternator or a Coil-On-Plug (COP) unit. This is accomplished by disconnecting the alternator and individual COP units one at a time to determine if the engine will stay running to potentially target a source of electrical interference. However, the ignition coils are tough to get to and again, you will set additional trouble codes that will even when reinstalled may keep the engine from running correctly. note, do NOT drive the vehicle with a coil unpluggedDue to the fact that the PCM is heavily reliant on the MAF input for engine load calculation, a low input of the MAF could potentially cause the PCM to set these codes.Also, be sure to visually check the wiring, I've seen the sensor wire rub thru on the power steering fluid reservoir. Again, please feel free to ask any questions you may have.
Expert:  Adam Legler replied 1 year ago.
Hello again, just wanted to touch base and see if you had a chance to either test the MAF sensor and/or if your poor running has returned after the reset of the PCM. Just a reminder, please feel free to ask any questions you may have, I'm here to help! Thank you