John Deere 450H LGP Dozer Won't Start Code F9AA & No Power To Injector Solenoid

[Bucktooth7]

This machine has got me scratching my head, I know it's got to be something simple I am overlooking. I have the shop manuals but they aren't doing me any good. I need some new ideas

I have a 2003 John Deere 450H LGP dozer with 1900 hours. Last time I used it a code of F9AA came up and the dozer would not accelerate. It went down to a complete crawl. I parked it for a day, and started it, it ran fine although the F9AA code was still on the gauge. About 2 hours into the job the same thing happened. The machine was down to a crawl. I talked to a JD dealer, I was told it was the computer and it was a common problem. I was told a new computer was $2000, Is that correct? I can't even locate the computer on the machine. Any ideas where to look?

After parking the dozer for the winter months, now I can't get it started. I have fuel the injector pump but it appears I have no power to the injector pump solenoid. Do you think this goes back to the F9AA code and the computer issue? I checked all the fuses in the block and nothing was blown. Looking for some ideas

Thank You
Bucktooth7

 

[eric12]

the computer is usually covered by a black plastic case behind the operators seat and sometimes they get water in them or the connections get dirty/ corroded. you might be able to just disconnect the computer and clean the connections good then put dielectric silicone on it to help keep it clean. ive also heard of on a rare occasion a terminal in the plug getting loose or becoming bad/ worn out and a single end gets replaced.

 

[Bucktooth7]

Thank you I'll take a look and see if that may be the problem. Do you think that would keep me from getting power to the fuel injector solenoid?

 

[Bucktooth7]

I removed the computer looked at all the electrical jacks, they look like new. I did put dielectric gel on the pins. But No Luck. Still shows fault code F9AA on the instrument read out. Engine cranks but no power to the injector solenoid (the manual says when the ignition is turned on you should hear a click at the solenoid, I don't) also checked the power leads at that point with the ignition turned on, and no power. Anymore good ideas out there? Thanks again

 

[thepumpguysc]

Kinda depends on what injection pump is on your engine..If the pump name plate says DB2 OR DB4 its a pretty easy dignostic..IF it says DE then your looking at trouble[$$]
If its a DB then just run a power wire from the battery to the + side of the top cover where the solenoid is located and listen for the click. OR remove the top cover [3 screws]
As far as the LOSS OF POWER TO the solenoid, its probably a matter of shut down sensors..overheat or oil pressure.. Locate each sensor, unplug them and "paper clip" the plug in connector 1 at a time until the engine continuse to run and you found your bad sensor.

 

[Bucktooth7]

Sounds like a good approach, I do have a DE fuel injector pump. I am curious as you mentioned with the DB pump, with the DE pump/solenoid can I try to take power from the battery (+) side to the injector solenoid to see if if I get the "click" I would think that would tell me that the DE pump/solenoid would function properly if power was able to get to it? If this works, any idea where I look for the overheat and oil pressure sensors? I really appreciate your expertise.

Thanks again!!

 

[thepumpguysc]

I dont think thats wise..the power supply to and from the pump is measured in MILIVOLTS and miliseconds..read and controlled by the computer..
There is away to clear the codes by removing the neg. cable from the battery for about 10 minutes.

 

[Bucktooth7]

Thanks for the heads up. I will try disconnecting the negative terminal on the battery to see if it will reset the computer, but I would think turning the battery disconnect switch to the off position (which is what I do when the machine is not in use) would have the same affect on the computer. At this point I will give anything a try. Thanks again !!!

 

[AndrewC]

Hey there, here are a couple of things to check. First check the battery terminals they need to be clean and tight. Check the connectors at the starter, the ecu takes its power from there and deere had a batch of bad crimps there. Also check for the fuse by the alternator and have a look at the connectors there as they tend to get a little damaged over time.
A note about the battery disconnect, the computers usually have constant power regardless of the disconnect. Could be a computer though too, but its better to start with the easy things.

 

[Bucktooth7]

As far as the micro processor transmission control unit, I have seen on line there are quite a few John Deere dozer owners that have had to replace the micro processor unit. I have seen references indicating these units cost about $1800, however I called a local JD dealer and was quoted $3100. Can this be correct? Are they available for less? Where were they purchased? Thanks

 

[AndrewC]

Last time I changed one it was on a j dozer but it was $3300. Check your power side because if the ecu receives too low of a voltage then it won't run and it will throw that code. I have seen it before and I know for sure I'm not the only one as there are several cases for it in the jd system.

 

[Bucktooth7]

Hi Guys, I'm Back

The John Deere 450 H still appears to not be getting any power to the injection pump solenoid. Although I did have a moment in time where it appeared the machine was getting fuel and the solenoid was working but it wasn't for a long enough time for the engine to catch. Then it went right back to the engine cranking and no fuel pumping. Any more ideas? I have cleaned all electrical terminals at the battery, starter, injection solenoid etc. I have tried disconnecting the battery to see about resetting the computer, I have checked all fuses, and made certain there is no air in the fuel system. Any more ideas Thanks again for your thoughts!!!

 

[thepumpguysc]

Did you find a solution?? I was told that if you pull one of the sensor connectors off, coolant or oil pressure..and test the wires with the key on you should get 5 volts at the wire.. that will tell you IF the computer is "powering up".. You need to do this test w/ 2 people..1 to read the meter and 1 to turn the key on and off..
Just because your not getting a feed to the inj. pump solenoid doesnt mean the pcm is bad..it just means that the system check showed there was a problem and cut the feed to the inj. pump..TEST THE SENSOR CONNECTIONS.. and PLEASE let us know..

 

[Bucktooth7]

Thank you to everyone for your good suggestions. Surprisingly this was a very simple inexpensive fix (0.75 cents). The problem was a blown 10amp fuse in the fuse block (fuel shut off). The bulldozer started instantly and runs as good as new.

Thanks again for all your help!!