Fire Commander Problems DDEC III

[Recelect]

I am working on a Detroit Diesel Fire commander. The problem I am having is it will not go into pressure mode. This is on a 2001 Spartan chassis with Smeal Body.

This unit was replaced about 6 months ago and has had problems from day one. The old fire commander that it replaced also had problems switching modes, but the INC and DEC buttons were the only buttons that worked, so we figured the mode button had gone bad.

I have tested the I/Os, pressure transducer, and wire harness, and I have all the signals that I need to allow it to go into pressure except the signal returning from the DDEC III ECU after the mode button is pressed.

Now, here is what is weird. If the truck is in pump and not running, The commander will switch modes, which says to me the signal is getting to the DDEC and Returning, but once the engine is running, the signal that allows it to switch to pressure is lost and once again I cannot switch modes and it sets its self back to RPM.

Also, the Tach in the instrument cluster sometimes works, and sometimes doesn’t. Could this be related? The Tach on the fire commander reads correct all the time.

Thanks for your help in advance!

[FWDbuff]

I am working on a Detroit Diesel Fire commander. The problem I am having is it will not go into pressure mode. This is on a 2001 Spartan chassis with smeal Pump. Check that- Smeal does not make pumps, they are a body manufacturer. It is probably a Waterous or Hale pump.

Now, here is what is weird. If the truck is in pump and not running, The commander will switch modes, which says to me the signal is getting to the DDEC and Returning, but once the engine is running, the signal that allows it to switch to pressure is lost and once again I cannot switch modes and it sets its self back to RPM.

At my former career department, we operated a 2003 Pierce Pumper-Tanker with a 60 Series DD, one of the first generations of the Allison World Series automatics, and a Waterous pump. Had a Fire Commander, and we experienced similar problems. Motor Pool was clueless. Kept returning it to us with the "we can't find anything wrong" look on their faces. Out of curiosity I started playing around with it one day, got the same thing- truck shut off but in pump, commander started working. IIRC, it was traced back to a communication problem between the engine, the transmission, and the commander.

[Recelect]

At my former career department, we operated a 2003 Pierce Pumper-Tanker with a 60 Series DD, one of the first generations of the Allison World Series automatics, and a Waterous pump. Had a Fire Commander, and we experienced similar problems. Motor Pool was clueless. Kept returning it to us with the "we can't find anything wrong" look on their faces. Out of curiosity I started playing around with it one day, got the same thing- truck shut off but in pump, commander started working. IIRC, it was traced back to a communication problem between the engine, the transmission, and the commander.

I fixed the Smeal Pump thing. Thanks for pointing out my typo.

I would think a communication issue would cause an engine light, or a diagnostic code. What about an incorrect setting on the commander, or in the engine computer? I don't know how it could have changed in the engine computer, but there are things that have to be set to make the commander work. Has anyone had issues loosing settings? can anything be changed on the commander?

[MG3610]

I fixed the Smeal Pump thing. Thanks for pointing out my typo.

I would think a communication issue would cause an engine light, or a diagnostic code. What about an incorrect setting on the commander, or in the engine computer? I don't know how it could have changed in the engine computer, but there are things that have to be set to make the commander work. Has anyone had issues loosing settings? can anything be changed on the commander?

I am not a mechanic, but I recall that DDEC systems have a dedicated battery for the system. Have you tested the batteries?

[FWDbuff]

I fixed the Smeal Pump thing. Thanks for pointing out my typo.

I would think a communication issue would cause an engine light, or a diagnostic code. What about an incorrect setting on the commander, or in the engine computer? I don't know how it could have changed in the engine computer, but there are things that have to be set to make the commander work. Has anyone had issues loosing settings? can anything be changed on the commander?

I can competently trouble shoot and repair my 1958 F.W.D. with a Waukesha gasoline engine. When you start to talk about the computers this, setting that, modes or diagnostics, you are now speaking Swahili. (Not to mention it is way beyond my pay grade.)

[FIREMECH1]

I'm not familiar with the fire commander system.

But, the comment on the DDEC dedicated battery is a sure possibility of causing your problems.

Good call MG3610.

FM1

[Recelect]

I'm not familiar with the fire commander system.

But, the comment on the DDEC dedicated battery is a sure possibility of causing your problems.

Good call MG3610.

FM1

So, As far I as know, there are a total of 6 batteries in this truck, and they are all wired in parallel. 3 on each side. should I be looking at this as a dedicated Bank of batteries to the DDEC? I was nearly positive they were all together.... Would this cause other issues too? I would think we would be having engine problems as well....

[FIREMECH1]

The battery should be a small 12v motorcycle sized one. It should be mounted on the drivers side, next to the battery box holding the 3 larger batteries. Sometimes they are just to the right of it, or on the frame under where the driver sits.

We usually replace it as soon as we get strange happenings or driveability issues. Most of the time it takes care of the problem.

FM1

[EVTRon]

While the issues with an isolated battery, as stated in previous posts, can cause the problem you have, I doubt the truck has an isolated battery for the DDEC. By 2001, most manufacturers were not using this due to all the problems experienced in the early 1990's.

I would check the ground for the Fire Commander first. It MUST BE GROUNDED TO THE BATTERY. Too many vendors were guilty of grounding pressure governors to the pump panel or pump module structure. A rule of thumb is that the governor and the engine ECM must share a common ground. The best place for this is directly to the ground post on the battery and the ground wires touching each other on the same post. I know it sounds like overkill, but I have fixed many governors of differnent brands just by ensuring that the govenor is grounded properly.

Since the problem appears when the motor is running and clears up with the motor not running, grounds would be suspect. Poor alternator grounds can generate noise that can corrupt the signals to the ECM. Next, check the J-1957 Data Link. There could be excessive noise in the data link that will disrupt the signal. If you have a laptop with DDDL diagnostic program, you can watch the data on the ECM and see if you see something fishy. It could be something not related to the engine and governor that also shares the J1587 data link. I believe the tach on the instrument cluster is also driven by the J-1587 data link, but I am not completely sure on that.

Finally, if the governor has been damaged so that water can seep into the governor panel, it will cause the same problems that you are seeing. Water and electronics do not play well together.

You are correct that the ECM must be properly programmed for the EFC to operate, but that should not be an issue unless someone has changed the program or the ECM was replaced and not properly programmed.

On DDEC III, the J-1587 data link will not always set a Diagnostic Trouble Code.

I know this is a lot of info, but check the ground first.

Good Luck,

Ronnie

[rm1524]

Another thing to check is the plug from the control head to the ECM. We had one that when it was plugged in at the factory they had broken a prong off in the plug and it was making poor contact and causing the controler to do a kinds of crazy things.

[Recelect]

While the issues with an isolated battery, as stated in previous posts, can cause the problem you have, I doubt the truck has an isolated battery for the DDEC. By 2001, most manufacturers were not using this due to all the problems experienced in the early 1990's.

I would check the ground for the Fire Commander first. It MUST BE GROUNDED TO THE BATTERY. Too many vendors were guilty of grounding pressure governors to the pump panel or pump module structure. A rule of thumb is that the governor and the engine ECM must share a common ground. The best place for this is directly to the ground post on the battery and the ground wires touching each other on the same post. I know it sounds like overkill, but I have fixed many governors of differnent brands just by ensuring that the govenor is grounded properly.

Since the problem appears when the motor is running and clears up with the motor not running, grounds would be suspect. Poor alternator grounds can generate noise that can corrupt the signals to the ECM. Next, check the J-1957 Data Link. There could be excessive noise in the data link that will disrupt the signal. If you have a laptop with DDDL diagnostic program, you can watch the data on the ECM and see if you see something fishy. It could be something not related to the engine and governor that also shares the J1587 data link. I believe the tach on the instrument cluster is also driven by the J-1587 data link, but I am not completely sure on that.

Finally, if the governor has been damaged so that water can seep into the governor panel, it will cause the same problems that you are seeing. Water and electronics do not play well together.

You are correct that the ECM must be properly programmed for the EFC to operate, but that should not be an issue unless someone has changed the program or the ECM was replaced and not properly programmed.

On DDEC III, the J-1587 data link will not always set a Diagnostic Trouble Code.

I know this is a lot of info, but check the ground first.

Good Luck,

Ronnie

Thanks Ronnie. Tell me, do you or anyone else know the difference between Ground type 2 and ground type 4? I only ask because this is how it is labled at the Tach. The tach is the only thing that has a different type then the rest of the instruments and lights on the dash, it would be good for me to know...

[EVTRon]

Recelect,

Without the Spartan schematics, I am only going to hazard a guess. I remember on the newer Spartans, they have common or "dirty" grounds and they had a different circuit number for a "clean" ground for the electronics (especially multiplexing). My memory is a little fuzzy on which one is which.

The tech support group at Spartan can tell you what the ground circuits are. They have a pretty good group up there and have always been helpful to me.

Ronnie