Make sure you check the LPG sensor wires carefully for the ecm cycles the fuel lockoff. If the low then the lpg pressure sensor signals the ecm to cut on the fuel during start up. If pressure is normal during start up the the lock-off will not open up untill the injector has bled off enough fuel/ pressure to open the lock-off.

Hope this helps

there are a couple of "learn in" procedures that should be done when replacing and ECM, and one of them requires the cable and software, also worth being concerned about is the 'model year' break in the ECU. there is a different ECM for trucks with the pressure sensor on the top of the throttle body than trucks with the pressure sensor screwed into the side of the throttle body. you do confirm that the code shows up while the engine is running and not just when you first turn on the key (can not reads the hour meter at all).

Well, have been through the wringer on this one. After checking every wire in the system and confirming all the connections were good the lift would no longer start. Found we were not getting a signal from the ECU to the relay for fuel solenoid. We replaced the ECU thinking this would take care of all the problems. We now show a code of E-21, mass air flow sensor. We tried swapping with a known good running lift with no change. When replacing the ECU is there anything that must be calibrated or loaded to ensure the lift is running properly? Thanks for any help.

Are you sure the pedal dance worked.
If not even while the errors are alreaday repared the errorcode keeps showing up on the dash.

Is the errorcode on the dash all the time or only with the ignition on whilest the truck is not running?
If the errocode only shows with Ign on but Engine not running that indicates that this is an recorder arror but not an actual error.
Does the engine run properly?

If there was a bare wire that shorted to ground for the MAF sensor then is a possibility that the ECM got damaged and needs replaced,is a possibility anyways.

A bad regulator/high psi will throw a code E-38 so I doubt that is the problem

Have checked all the wiring for each code and find nothing wrong. Could a bad regulator or pressure to high cause this problem? Not sure what else to check. Cleaned all the grounds and checked the charging system along with the battery. All is good. Anything else you can suggest would be a great help. Thanks.

the wiring in these trucks has proven to be somewhat crappy
get alot of breakage at the connectors where they plug into the components.
pull on the wire, you can tell if there is a break because it will pull out most of the time.

in most cases you can solder the wire back but if its broken too close to the connector then that might not work. a new harness would be required.

one other thing to check if your getting random codes popping up is the negative ground at the frame on the left side just behind that ECM, pull the wires off and clean the frame from any paint, make sure its clean and reinstall the connection.

just remember, you can try the 'pedal dance' to clear the codes but if they return immediatly then the problem is persistant and will not clear until you repair whats causing them.

Kevin,

Thanks for all the information it has helped a lot. I have not tried to do the pedal dance yet but have disconnected the battery for at least 10 minutes and the code still comes up. Found a bare wire going to the air flow sensor which was shorted to ground. Repaired the wire but still have the code. Tried testing for output voltage at the sensor but hard to get a good connection. Would the air flow sensor burn out if a wire is shorted to frame? Not sure how to check the throttle position sensor with out a breakout harness. And yes, both of the codes set at the same time. Thanks.

Code E-21 is Mass air flow sensor signal circuit malfuntion
Code E-23 is Throttle position sensor signal Circuit Malfunction

Did both set at the same time? seems strange for these two,one thing i would check is the battery condition and make sure the Alt. belt is tight. Sometimes can get some strange codes if battery is getting bad or belt is loose,as for clearing the codes follow the instructions,tho the throttle code might not clear with the pedal dance,might have to unhook the battery cables for a bit to clear them.

"The Pedal Dance"
Turn the ignition switch on with accel. pedal released,after 3 seconds fully depress the accel pedal 5 times within 5 seconds(end in released position). After 7 seconds(timing is very important...1 mississippi 2 mississippi etc....) press and hold down accel pedal for approximately 10 seconds(again timing) until the hour meter starts blinking, release pedal and push down and hold again for 10 seconds) hour meter should be on with no codes showing,shut key off and test to see if codes cleared.