I know this is a Tremor forum but there seem to be enough non-Tremor owners here so a discussion about 6.0 isn't too far out in left field. It is still a Ford, after all—what difference does it make?
I've got a 2007 SD with a 6.0L and I am calling all 6.0 gurus—are there any besides @HeavyAssault and possibly @JTredway?
My 6.0 with 375K on the clock has started acting up the last couple days. A few months after installing new batteries, the wrench light came on. I pulled a code for a cylinder 1 glow-plug circuit fault. Since I live in the desert and it was midsummer, I was not too concerned. After a few thousand miles, the wrench light went away.
A few days ago, the check-engine light came on while I was driving around town. It was off by the time I got home, but the next morning both headlights were out. That seemed strange, especially since they failed at the same time. I let my diesels idle for 10–15 minutes before driving away, and by the time I was ready to leave, the headlights were working again. I suspected a short, loose connector, or an issue with the LED wiring—but why would both lights fail simultaneously?
The next day, I finally had time to dive into the issue. I pulled the headlight fuses and found their blades bent and oddly discolored—not a good sign. Several nearby fuses looked similar, so I replaced every affected one I could find. At that point, I suspected a short might also be causing the cylinder 1 glow-plug circuit fault.
My first step was checking the battery terminals. The driver-side positive terminal was so loose that I could pull it off the post by hand. I thought I had found the problem—then my first concerns were the FICM.
I checked and tightened every terminal on both batteries, then replaced the four discolored fuses in that row. Afterward, all warning lights and other issues disappeared.
That was about four weeks ago.
I started the truck this weekend. Although I keep it on a NOCO 5-amp slow charger, it is usually a little slow to fire on the first few starts. The starter itself turns normally—I have a 6.4 starter in her—but the engine takes longer to catch until it warms up and gets a few miles on it. This time, however, it was still slow to start after about an hour of errands and roughly 60 highway miles. Suspecting the batteries, I tested them when I got home. Both showed a full charge and good condition. They are Costco Interstate batteries dated 12/25.
I then checked then checked the alternator, with the engine running and it tested at 14.0 volts.
My next suspect is the FICM, although I know they usually fail because of another problem—often low voltage or, in this case, loose terminals. Could I have damaged it? The truck has no white smoke, unburned-diesel smell at idle, rough idle, or loss of power, she just seems slow to catch on start up. Not terrible but enough to concern me.
A few years ago, a former employee ran the old batteries nearly dead. I discovered it when I noticed the engine struggling to turn over; one battery was so damaged that its case had bulged. Since then, I have stopped using this truck as a work vehicle. These trucks are sensitive, and not everyone handles them carefully. She's now my weekend driver.
I've got a 2007 SD with a 6.0L and I am calling all 6.0 gurus—are there any besides @HeavyAssault and possibly @JTredway?
My 6.0 with 375K on the clock has started acting up the last couple days. A few months after installing new batteries, the wrench light came on. I pulled a code for a cylinder 1 glow-plug circuit fault. Since I live in the desert and it was midsummer, I was not too concerned. After a few thousand miles, the wrench light went away.
A few days ago, the check-engine light came on while I was driving around town. It was off by the time I got home, but the next morning both headlights were out. That seemed strange, especially since they failed at the same time. I let my diesels idle for 10–15 minutes before driving away, and by the time I was ready to leave, the headlights were working again. I suspected a short, loose connector, or an issue with the LED wiring—but why would both lights fail simultaneously?
The next day, I finally had time to dive into the issue. I pulled the headlight fuses and found their blades bent and oddly discolored—not a good sign. Several nearby fuses looked similar, so I replaced every affected one I could find. At that point, I suspected a short might also be causing the cylinder 1 glow-plug circuit fault.
My first step was checking the battery terminals. The driver-side positive terminal was so loose that I could pull it off the post by hand. I thought I had found the problem—then my first concerns were the FICM.
I checked and tightened every terminal on both batteries, then replaced the four discolored fuses in that row. Afterward, all warning lights and other issues disappeared.
That was about four weeks ago.
I started the truck this weekend. Although I keep it on a NOCO 5-amp slow charger, it is usually a little slow to fire on the first few starts. The starter itself turns normally—I have a 6.4 starter in her—but the engine takes longer to catch until it warms up and gets a few miles on it. This time, however, it was still slow to start after about an hour of errands and roughly 60 highway miles. Suspecting the batteries, I tested them when I got home. Both showed a full charge and good condition. They are Costco Interstate batteries dated 12/25.
I then checked then checked the alternator, with the engine running and it tested at 14.0 volts.
My next suspect is the FICM, although I know they usually fail because of another problem—often low voltage or, in this case, loose terminals. Could I have damaged it? The truck has no white smoke, unburned-diesel smell at idle, rough idle, or loss of power, she just seems slow to catch on start up. Not terrible but enough to concern me.
A few years ago, a former employee ran the old batteries nearly dead. I discovered it when I noticed the engine struggling to turn over; one battery was so damaged that its case had bulged. Since then, I have stopped using this truck as a work vehicle. These trucks are sensitive, and not everyone handles them carefully. She's now my weekend driver.
![What did you do to your Tremor today? [2026 edition]](https://www.fordtremor.com/data/files/featured_images/featuredimages_thumb_2.webp?1792533398)
