Attention: TDR Forum Junkies I have finally solved the issue, but first let me describe my problem. Everything started when the truck died on the freeway (in July- dash out, P2509). At the time I thought replacing the original batteries fixed the problem, but I was wrong. Then I started getting a "Check Gages" light, and rough ilde. The voltage was constantly changing from 14-16+ volts, then it would settle at 14. 2 and everything would be fine. It sounded bad enough to park it.
What I tried...
1) New Batteries (tested one set, eventually swapped in a second set), and tested battery temp sensor - no change
2) Clean and inspect all ground cables - no change
3) Bypassed the cross over cable - no change
4) Replace the alternator - no change
5) Had the dealership test it (a very difficult thing for me to do) - the said it was the ECM
6) I replaced the ECM - no change. At this point I knew I was in for a lot more work. I figured the voltage regulator in the ECM was bad causing the irregular voltage.
7) Load tested the alternator - pass up to 120amps without a hint of issues.
8) what the heck do i do now??? It has been parked for months now. So, I started mapping voltages and currents. nothing seemed out of place- I really thought the high amp draw of the heaters was the issue - mapping proved that was not the case.
9) Noticed the negative battery cable slightly out of the terminal. Made a bypass - everything seemed to be perfect. The truck ran for 30min without issues! Shut the hood for test drive- idle surge, started running rough.
10) after a few f bombs, i was done for the day. i knew it was wiring, but needed a break.
11) wire wiggle. start wiggling wires while running with the code reader on. Wiggled a wire and the truck shut off... P2509 - PERFECT. The wire... specifically... 8W-20-4 in the service manual. It is the power wire from the integrated power module (fuses) to the ECM. I cut out the old mess, built a new wire (with fusible link), and the truck runs great. This is day one, but I don't have any idle or voltage issues.
I hope this helps someone else. I have been working on this since July, it was parked in September. I am happy to be back on the road!
What I tried...
1) New Batteries (tested one set, eventually swapped in a second set), and tested battery temp sensor - no change
2) Clean and inspect all ground cables - no change
3) Bypassed the cross over cable - no change
4) Replace the alternator - no change
5) Had the dealership test it (a very difficult thing for me to do) - the said it was the ECM
6) I replaced the ECM - no change. At this point I knew I was in for a lot more work. I figured the voltage regulator in the ECM was bad causing the irregular voltage.
7) Load tested the alternator - pass up to 120amps without a hint of issues.
8) what the heck do i do now??? It has been parked for months now. So, I started mapping voltages and currents. nothing seemed out of place- I really thought the high amp draw of the heaters was the issue - mapping proved that was not the case.
9) Noticed the negative battery cable slightly out of the terminal. Made a bypass - everything seemed to be perfect. The truck ran for 30min without issues! Shut the hood for test drive- idle surge, started running rough.
10) after a few f bombs, i was done for the day. i knew it was wiring, but needed a break.
11) wire wiggle. start wiggling wires while running with the code reader on. Wiggled a wire and the truck shut off... P2509 - PERFECT. The wire... specifically... 8W-20-4 in the service manual. It is the power wire from the integrated power module (fuses) to the ECM. I cut out the old mess, built a new wire (with fusible link), and the truck runs great. This is day one, but I don't have any idle or voltage issues.
I hope this helps someone else. I have been working on this since July, it was parked in September. I am happy to be back on the road!
