24Volt Cat C15 ECM convert to 12 Volt ?

[MBX1]

I have a 08 Cat C15 removed from a 24v truck and installed in 12v system truck, can the ecm be "reflashed" or do I need a 12V ecm? My Cat dealer is looking into it but I thought I would pose the question to you,

 

[Nige]

Engine Serial Number..?
IIRC a Cat engine ECM will operate satisfactorily on anything from 10-30V DC, but I need to check on that in the case of the specific ECM Part Number installed on this engine.

 

[MBX1]

ser# is KRA000697, it does run although it is de-rating or going to limp mode, the Caterpillar tech showed me on his laptop where its showing low ecm voltage at 14.3 volts and throwing a code, leading us to believe it's expecting 24v

 

[Nige]

Do you know what code it is generating..?

 

[MBX1]

Nige, I don't know the specific code he was getting at the shop, I can only get the flash code (51) which is not very specific

 

[Nige]

The KRA-prefix engine is only designed to work with a 24V ECM. In case you weren't aware the engine you have came originally from an Oshkosh truck supplied to the US military. It's rated at 500BHP @ 2100RPM and shipped from the factory in September 2008.

There are other C15 models that list 12V ECMs, specifically the SDP-prefix engine. It lists 2 Part Numbers for a 12V ECM, 272-3366 & 289-1531. Both appear from the Parts Manual to be physically similar to the 226-7469 that is installed in your engine. I say "appear to be" because sometimes the Parts Manual diagrams are not a true reflection on what the part physically looks like. What software would have to go into it is a matter for debate ........ 308-7254 is what's in it now.

Does the engine have a compression (Jake) brake installed..? Out of what are literally hundreds of possibilities there are very few 500 BHP configurations of SDP-prefix C15 model engine rated at 500BHP @ 2100RPM with 12V electrics that do NOT include a compression brake. I'll list them here - 317-0431, 319-4794, 341-1254, 341-1257 (all for Paccar installation), and 343-7501, 343-7512, 297-8106, 297-8122 (Freightliner).

Don't forget that you may need to change all the engine sensors and the fuel injectors because like the engine ECM they may only want to run on 24V as well .............. at the end of the day you might be better changing the truck to 24V TBH.

As another thought consider the possibility that it may be a "dodgy or out-of-range" signal coming from a 24V sensor (maybe oil pressure or coolant temp) that is only operating on 14.3V that could be causing your engine to go into limp mode.

 

[MBX1]

Thanks Nige, yes the engine has jake brake, I purchased the engine from a government auction. I had not thought too much about the sensors or the injectors for that matter since it starts and runs great, (it only has 85 hrs on it), Think I may approach this from the parts dept. get a parts breakdown from the arrangement number 274-5161 and research from there,
Thanks

 

[MBX1]

I knew the oshkosh truck was 24v because of the starter and alternator that came installed on the engine, I was hoping it was a dual voltage set up or at least the ECM could be reflashed,

 

[MBX1]

I guess my next question is how many amps of 24v power would it take if just wanted to power the engine, It only has one 10amp and one 15amp fuse powering the whole ECM, couldn't I just step up the voltage to the ECM ?

 

[Cmark]

Nige. I'm not saying you're wrong, but where did you find a reference to specific 12 or 24V ECMs? I also thought they were OK with either voltage.

Looking on SIS, I see a software switch for "Vehicle Voltage Selection". It's in the configuration parameters along with FLS and FTS.

I could be completely wrong, but my guess would be to change the parameter to 12v, change the Jake solenoids to 12V ones, there's also a couple of 24V solenoids in the precooler system which will need changing and you should be good to go.

 

[Nige]

I was looking in C15 SDP-prefix. It lists different ECMs for 12v & 24v. All the engine arrangements I could find for KRA prefix C15 have 24v electrics.

 

[Cmark]

I was looking in C15 SDP-prefix. It lists different ECMs for 12v & 24v. All the engine arrangements I could find for KRA prefix C15 have 24v electrics.

Ah yes, I see. Although for that particular prefix I can see 12V 3722912 and 24V 4222302, but both go to 10R6199 so it's not immediately obvious why there's different part numbers.

However, KRA takes a 10R5649 which also fits (amongst others) MXS, which can be either 12 or 24V, so I (reservedly) stand by my earlier comments, your honour.

 

[Nige]

It really needs ET hooked up to the ECM and take a good look at the configuration screen to see what customer-settable parameters there are.

 

[Nige]

Edit (Sunday) - had a good look at what CM was referring to in his post last night. Note to self, working from a tablet in the pub is not the best method to get results.

It appears CM is correct, there is a parameter in the Configuration for "Vehicle Voltage Selection" which, and I quote ........ "The "Vehicle Voltage Selection" parameter determines the upper limit and the lower limit for battery voltage, that is used in order to trip the diagnostic codes for battery power. The options for programming are 12 volt or 24 volt. Typically, the parameter is set at the Caterpillar manufacturer, based on the engine order."

As this engine originally went into a 24V truck then the voltage would have been set for 24V when it left the factory. I would guess that what's happening now the engine is installed in a 12V truck is that the ECM is generating a diagnostic code for "Low battery voltage". With ET it ought to be a simple matter to change the setting from 24V to 12V.

 

[MBX1]

Thank You, Nige and Cmark, through my research it says the "actuator group-valve" Pn 2497187 is 24v , is that because of jake solenoid only or is there a difference in the "VVA" solenoids also? the only other 24v part i find is coolant diverter valve Pn 2307566, am i missing anything else ?

I could easily obtain and change out the three jake solenoids and coolant diverter valve, and of course get my Cat technician to fix the ECM voltage, if thats all it takes I will be happy!

 

[Cmark]

The three 24V Jake coils are 2509378. I'm not sure what you mean by VVA solenoids. I can't find a reference to that?

The coolant diverter valve has a 24V coil 3013118.

There's also an IVA warm up valve with a 24V coil 2369837.

If you need part numbers for the 12V versions, I can look them up later today when I have more time, or Nige or someone else will come along. But your Cat dealer should be able to look them up as well.

As far as I can tell, those are the only hardware changes you'll have to make. However, once the ECM has been set to 12V, if there's any other components it has a problem with, it should show a fault code.

(BTW, the "Jake" brakes are now called "Cat" brakes, so I assume they're no longer made by the Jacobs company, possibly due to being out of patent?)

 

[Nige]

While we're looking into the other issues the first thing I would do is go into the ECM and to change the voltage setting to 12v. See if that change makes your diagnostic code go away, if it does then obviously we're on the right track.

 

[MBX1]

I will see if I can get it to the shop tomorrow

 

[lantraxco]

Edit (Sunday) Note to self, working from a tablet in the pub is not the best method to get results.

Huh! It always worked so well for me!

 

[Nige]

It tends to pi$$ the wife off as well ............ if we're in less-than-sparkling company I'm not good at hiding the fact I'm bored.