10/15 Ser # HP2389
Truck was parked for about 6 weeks and batteries were totally dead. Recharged batteries, nothing was unhooked, then starter would spin engine but not start. Pumped hand primer and tried again. Then it would no longer crank. Acted like a bad switch, and still does, When the key was turned sometimes the starter would bump. If the key was worked back and forth in the crank position some times in would bump and after a minute or so it would crank and start.. Dead pedal and DEF gauge red light was on. Shut off and added DEF fluid. no change. Then noticed tach, oil and temp gauges do not work. Tightened battery cables and inspected everything there. Tightened all connections on and around starter. That did not fix anything but found that some times the gauges will work and the DEF gauge has 3 green bars when they do. Pedal remains dead and key does not work properly for a restart. Connected push button to small solenoid before starter solenoid. Starter works great. Checked all fuses , 3 boxes LF firewall, one in front of glove box and ignition switch - OK. Turned on ignition switch, lights and blower motor. Checked for Battery voltage at all these places. All were good except for ignition switch feed is 1 1/2 V low. Connected a jumper from battery to switch. That made no difference Voltage drop tested grounds. Frame, cab, starter, etc, found no problem. Batteries have been disconnected for hours, no change. Could not read any codes to start with. Now it has a code: 43150F SPN 5443 FMI 15. Diesel Laptop will not clear it or do a forced regen. Check trans light flashes on dash but scanner reads no trans codes?
Any ideas?
Cascadia dead pedal and other issues.
Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by BoxCarKidd, Aug 6, 2025 at 4:46 PM.
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2017 Cascadia. When my CPC went bad. That computer in the dash next to the radio.
I had a dead pedal and that same code. I called a dealer for help.
He said with the code you mention and a dead throttle, all most, always means a bad CPC.
I did not have the other issues you mentioned. The truck cycled normal, started and idled but would not increase RPM's.
DD15 Troubleshooting - Section 17.3 Common Powertrain Controller - Detroit Diesel Engine Troubleshooting
Good luck.BoxCarKidd and QUALITYTRUCK Thank this. -
Detroit engine? If so check the harness where it makes a hard turn,right by the compressor. May be rubbed through on the bracket it’s zip tied to.
@QUALITYTRUCKBoxCarKidd Thanks this. -
Sounds like CPC failure to me. 2013-2016 had the problematic CPC modules. You could try "covid fix" when the modules were on worldwide back order for over a year during covid we resorted to crazy ideas. You can easily remove the circuit board from the plastic shell of the module. Carefully bend the board back and forth so it sounds like cracking knuckles. Plug it back in and try. Works 75% of the time, but is only temporary until you get new one.
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I had the same issue in a 2014 Cascadia, it turns out a little water had dripped into the CPC from a leaking marker light. I pulled it apart, dried with compressed air, and no more problem. Apparently, the solder joints can break that link the chip to the board inside. Common problem. Theres a company that can resolder the board and prevent that from happening again, but it runs about $1000 and whatever the turnaround time is.
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