Scope & Scan - Service Repair

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Bits and pieces from the TST bays

Wednesday, July 1, 2015 - 06:00
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The TST/ATTS training center is also a full-time shop located north of New York City. Even though my days are long and my free time short, keeping my hands dirty keeps me current on the problems my students (and my faithful readers) are facing. Here’s a few we had recently.

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A Faulty Ford
We had a 2003 Ford Expedition 4.6L V8 with 110,552 miles come in with Diagnostic Trouble Codes (DTCs) P0135, P0141,  P0151,  P0161 and  P0443. The vehicle had already been to the Ford dealer, and they told the owner that the O2 sensors had to be replaced along with the PCM (Powertrain Control Module). Since the owner was not happy with the Ford dealer diagnosis (or the repair cost they were quoted), they came to see me. I checked the vehicle out, confirmed the DTCs and checked for Technical Service Bulletins (TSBs) and found one that related to our DTCs. We called a local parts store looking for a replacement for the PCM, but no one had a listing but the dealer.

The cost of this PCM was more than $800, so we wanted to make sure that it would solve the vehicle’s problems before we replaced it. We checked all the O2 sensors’ heaters for battery power and ground to make sure that the heaters actually worked. The O2 sensors were very difficult to reach, but we had to test all in order to rule out if they were good or bad. What we found was that the sensors had power but no ground — that is supplied by the PCM. We used a PowerProbe to supply a ground to test the sensors and found that they were capable of drawing the correct amount of current along with heating up properly. The problem of a failed PCM was now confirmed since we proved that the components (O2s) could function properly if they were provided with power and ground.

The vehicle owner did not want to spend a bunch of money on an old vehicle and asked us to find the most reasonable (read “cheap”) way of repairing it. Since the new unit was so expensive and there were no aftermarket units available, I came to remember a company called Ourecms. Years back I used this company and recommended them to my students because they would ship you a unit to try for $75.  Now remember that you are not working on your father’s Oldsmobile anymore and PCMs are not “plug and play” without reprogramming them. I thought since I have the Ford IDS I could get a used PCM and program it to confirm our diagnosis. So I decided to go to the computer and typed in and get a used PCM. The site was no longer available but what came up in the Google search engine was It was the same location in Pennsylvania where I had purchased PCMs years ago. I read through their site and found this, “Misdiagnosis no problem, if an electronic unit was ordered but a misdiagnosis was discovered, after the unit was installed, yes you may return our unit for a refund less a $75 test/restock fee and all shipping charges.” Wow, it was the same company that I used years ago to solve some hard problems after testing all the sensors, actuators and wiring only leaving the computer as the possible problem!

We ordered the PCM, installed it in the vehicle and reprogramed (Figure 1) the unit so the vehicle would have all the correct information and start. When you are programing a new or used Ford PCM you have to deal with their antitheft system PATS (Passive Anti-Theft Systems) and program the keys as well. Make sure to have at least two OE keys available or the procedure cannot be completed properly, and the vehicle will not start. You should also have all the key fobs for the vehicle and know if there is remote start available on the fobs. If that is the case you will have to program the fobs as well. Another important step when you program a vehicle is to utilize a battery maintainer and make sure you type in the vehicle VIN number and other important information.

After the programing was completed, the engine started up and ran great. I took the vehicle for a test drive to make sure that Mode $06 would display passing test results. I was lucky because after two of us drove the vehicle all the monitors except EVAP (evaporative emissions) were “Ready.” After the vehicle sat overnight, we test drove it again and completed all the monitors, confirming our repair.

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