R&R Tech
Author: Jerry Tipton
Subject Matter: Diagnosis
Vehicle Application: 2005 Ford F-150 4WD
Issue: Engine-related codes
Did you ever play the game “tag” when you were a kid? Most of us likely remember a lot of fun and laughter that seemed to come with the game. Next question: Have you ever had to play tag with a customer’s vehicle in your shop? We’ve all done this as well; it isn’t nearly as much fun as the kids’ game.
This story is about the grown-up “shop” version of the game. The vehicle in question is a 2005 Ford F-150 4WD with only 49,568 miles. It all started like so many others: It came in with erratic shifts, abnormal noise and metal in the pan. The vehicle also had two transmission codes: P0712 and P0713. Initial diagnosis determined that the unit had internal hard-part damage. A remanufactured replacement transmission was in order.
The job was sold and installed, a re-flash performed and final road test completed – done and out the door. Everybody was happy, and the story had a happy ending, right? Well, not quite.
After about a week we got a call from the shop for which we performed the work saying that the check engine light was on again and the unit might have a small leak. We brought the vehicle in to diagnose and found that it had three engine-related codes: P0059 (HO2S heater resistance Bank 2 Sensor 1), P0135 (HO2S11 heater circuit fault), and P0155 (HO2S21 heater circuit fault). None of these codes was present when we diagnosed it prior to the transmission installation, so tag, we were it.
We started with the visual inspection and found that the fill tube was damp but didn’t see anything physically wrong with the O2 sensors. We decided to pull the fill tube to reseal it, clear the codes and then road-test. During the road test everything was fine for about three miles, but while I was heading back to our shop the check engine light came on and the engine developed a misfire. I made it back to the shop and pulled into the parking lot, and the engine stalled. Power to the dash was lost, the engine would not crank etc. I asked myself, “What else can go wrong?!”
We found a main fuse that was blown, so I replaced it to try to get it back on the hoist. This ended up being a bad idea, as the vehicle started and drove into the shop but began to smoke. I shut it down and on inspection found that an ignition coil on the passenger side had melted. In addition, more codes were generated: P0352 (ignition coil B circuit fault), P0351 (ignition coil A circuit fault) and P2197 (O2 sensor signal stuck lean B2-S2). At this point I was thinking we must have pinched some wiring somewhere during the installation of the remanufactured unit.
With the vehicle on the hoist, the visual inspection revealed no wires that had been damaged during the installation of the transmission. The next step was to look at the wiring diagram to see whether the codes had any circuits in common. We found that all the related code component wiring shared the same connector going to the PCM. After tracing the wire loom from the PCM down, I found that the harness had worn through and shorted to the A/C tube, causing all the circuits to short to ground.
The interesting thing is that this was not an issue created during the installation but was a problem created over time. When we moved the fill tube to reseal, we had also moved the harness just enough to short all the bare wires that had previously worn through. I don’t know why this particular harness was so close to this A/C line to rub though, but we were able to repair it and correct the issue.
You would think that this problem, which had taken a long time to manifest itself, would have had to show some signs of problems prior to our installation, but we all know we don’t always get the whole story from the customer about the vehicles we work on.
After we repaired the harness and repositioned it to prevent it from rubbing on anything, the road test went fine and we were able to deliver the vehicle back to the customer. No more games with this vehicle, but I’m sure there will be another one in the door soon that’s ready to play a new game of tag.
Jerry Tipton is the diagnostician at Certified Transmission’s retail location at 132nd & “B” street in Omaha, Neb. He has been with Certified for 25 years and was in the industry several years before that.
