Posted: 10/16/2014 10:00:37 AM EDT
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My 2008 F150 4.6L V8 with 71k miles suddenly started running rough between trips on Sunday, with the check engine light coming on after about 5 minutes of running. I put on a code reader and it reported that #4 cylinder was misfiring. I am not a car guy, I just drive them around, so I called my mobile wrench who came over and verified the code and began further diagnosis by removing the #4 coil to check for spark. I started the truck and it turned over but refused to start. At this point I notice that Anti-Theft indicator on the dash had begun flashing rapidly and the truck would no longer turn over, just a relay click in the engine compartment. After consulting the owners manual, it is apparent that the Passive Anti-Theft System (PATS) has decided the truck is being stolen and it locked down the electrical. The internet is full of various wisdom on how to get PATS to reset, none of which worked. Dealerships will not give that information out over the phone, unsurprisingly. Called NTB just for fun and they suggested disconnecting the battery and shorting positive to negative with a jumper for 10 minutes. No joy. I spent a couple of hours going through each internet-provided "solution" and was unable to make any progress. Turn the key to run, doesn't start and the PATS light blinks rapidly. I found out how to start the dashboard diagnostics (key to Run, hold the trip/odometer select until diags start) and noticed two anomalies; the voltage on the battery was reading 11.7v and the PATS dashboard light began blinking a code: 15. A 15 code means "I don't recognize that key" (from memory, may not be exactly right). The key has an embedded chip which is tickled by a transceiver that sends a code to the PATS module. Internet wisdom seems to indicate that if the PATS module is not available the odometer will show all dashes instead of mileage. My odometer indicates the correct mileage, which seems to indicate that the PATS module and subsystems are at least talking to each other. That's my understanding at least, perhaps one of you will have more specific knowledge. Checked the fuses in the cabin for the PATS and other modules, did not find any that needed replacing. Found the fuses in the engine compartment, while none of them appeared to be in the fault path I checked them anyway. Again, none needed replacing. My wrench was out of his depth here, so I decided to tow it to a dealership to get it looked at. I picked the dealership whose service rep had been at least interested in trying to help me earlier, so Tuesday late afternoon the truck is loaded up on a flatbed and delivered for service. Wednesday afternoon the service rep calls me to say that they think the PCM ( Power train Control Module ) may be faulty or dead and wanted to know if I'd authorize more work to get it out and put it on a tester. I said yes since the work was going to have be done anyway to replace it if it really was dead. Then the kicker, it's an $800 part. No other word from them yesterday ( Wednesday ). Searching the interwebs, I find that PCMs for my make and model seem to be about $300. I get that it's a business and they have overhead, but getting fleeced $500 (just for the part, nevermind the labor) kind of pisses me off. And there is still the matter of getting the #4 cylinder firing again. I'm looking for advice on how to deal with dealership to promote a more positive outcome for me and ideas about what might really be wrong with my truck. Updated: The service rep called this morning with good news. He discovered that the part is covered by a warranty as is the labor to replace it, so the money issue is now not an issue. They have ordered the part and expect to have it tomorrow. I asked him if a bad PCM may have caused the misfire on #4 and he thought was possible but won't know for sure until the PCM is replaced and they can get it running again. Thanks for looking, I know what I wrote was pretty dense. I just wanted to get down all the facts as well as I know them to keep from causing miscommunication or misdirection. TL;DR Dealer is going to repair for free. |
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Quoted:
My 2008 F150 4.6L V8 with 71k miles suddenly started running rough between trips on Sunday, with the check engine light coming on after about 5 minutes of running. I put on a code reader and it reported that #4 cylinder was misfiring. Odds are that #4 Cylinder needs a Coil. That is the first thing which should come to mind with that code and a miss. |
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Quoted: Odds are that #4 Cylinder needs a Coil. That is the first thing which should come to mind with that code and a miss. Quoted: Quoted: My 2008 F150 4.6L V8 with 71k miles suddenly started running rough between trips on Sunday, with the check engine light coming on after about 5 minutes of running. I put on a code reader and it reported that #4 cylinder was misfiring. Odds are that #4 Cylinder needs a Coil. That is the first thing which should come to mind with that code and a miss. So the dealer got the PCM and installed it, #4 is still missing. They are going to replace the #4 coil and give me a call. |
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The tech swapped #4 fuel injector with another an injector from a different cylinder to see if the fault followed it. While he had the injectors out he cleaned them. After installation, no missing on #4 or the other donor cylinder. So the verdict is dirty injectors. |