Hot Starting Issue (Possible immobilizer problem)
Thread Starter
Junior Member
Joined: Jan 2014
Posts: 2
Likes: 0
Hot Starting Issue (Possible immobilizer problem)
Hey all,
I'm helping my Dad fix a starting issue with his truck. We're both great mechanics with old vehicles but we do have trouble with OBD2 vehicles as everything is bloody computerized these days.
Vehicle:
2002 Ford F150 Lariat
5.4L Non-Subpercharged with Tow Package installed
Symptoms:
Vehicle starts and runs fine. Drive it for more than a few minutes (enough time for it to warm up) and turn it off. It won't start. It'll crank over just fine, but no vroom.
After weeding through countless other internet posts of the same issue, I found one other symptom. When you turn the ignition on, the Odometer light will come up dashed when it won't start.
If you wait a reasonable amount of time, the problem will clear and it will run perfectly normal again. Once it's had time to cool I reckon.
Troubleshooting already done:
I've read through other posts on several forums and was originally lead to the direction of a possible fuel delivery issue. Because of this, we've changed the Fuel Pump relay, fuse and changed the fuel pump itself (this was also to change the fuel gauge sender as this was also acting a bit wonky).
After some extensive research, I found that the issue with the display is likely to do with the immobilizer. I have also read the fuel relay is connected to the dash, but this is also replaced, so unlikely the issue.
I've tried a few more minor things like blipping the alarm and stuff like that.
Alas, the problem still exists.
I'm looking for some direction to get this problem nailed down. Even if I have to take it in, I want some more information so the 'pros' don't just throw parts at it.
Are there any other relays that can cause this? Is there a reason it's only doing this once the vehicle is warmed up?
Any and all help appreciated.
Thanks!
-Eomund-
I'm helping my Dad fix a starting issue with his truck. We're both great mechanics with old vehicles but we do have trouble with OBD2 vehicles as everything is bloody computerized these days.
Vehicle:
2002 Ford F150 Lariat
5.4L Non-Subpercharged with Tow Package installed
Symptoms:
Vehicle starts and runs fine. Drive it for more than a few minutes (enough time for it to warm up) and turn it off. It won't start. It'll crank over just fine, but no vroom.
After weeding through countless other internet posts of the same issue, I found one other symptom. When you turn the ignition on, the Odometer light will come up dashed when it won't start.
If you wait a reasonable amount of time, the problem will clear and it will run perfectly normal again. Once it's had time to cool I reckon.
Troubleshooting already done:
I've read through other posts on several forums and was originally lead to the direction of a possible fuel delivery issue. Because of this, we've changed the Fuel Pump relay, fuse and changed the fuel pump itself (this was also to change the fuel gauge sender as this was also acting a bit wonky).
After some extensive research, I found that the issue with the display is likely to do with the immobilizer. I have also read the fuel relay is connected to the dash, but this is also replaced, so unlikely the issue.
I've tried a few more minor things like blipping the alarm and stuff like that.
Alas, the problem still exists.
I'm looking for some direction to get this problem nailed down. Even if I have to take it in, I want some more information so the 'pros' don't just throw parts at it.
Are there any other relays that can cause this? Is there a reason it's only doing this once the vehicle is warmed up?
Any and all help appreciated.
Thanks!
-Eomund-
Thread Starter
Junior Member
Joined: Jan 2014
Posts: 2
Likes: 0
We have a solution.
Broke down and took it to a shop we trust. They found it was the ECM Relay that was in the process of going bad. Replaced the $15 part, and Shazaam, the truck is going like it should again.
So a word to the wise out there. There are a number of relays that can cause this issue to pop up. It's just finding the right one.
Broke down and took it to a shop we trust. They found it was the ECM Relay that was in the process of going bad. Replaced the $15 part, and Shazaam, the truck is going like it should again.
So a word to the wise out there. There are a number of relays that can cause this issue to pop up. It's just finding the right one.