Quick question… 2000 freightliner with C12 engine. Took the ECM out and caterpillar tested it and said it was bad. We contacted Truck ECM out of Dallas Texas and they sent us a re-manufactured ECM in which we installed. Everything seems to be working fine except when the key is initially turned on the check engine light doesn’t come on during the test cycle and the air brake light doesn’t illuminate during low pressure build up. Not getting any dash lights. Truck cranks up and runs. Any thoughts? Please help! I’m afraid if i run the truck like this the engine light might not work at all and not come on when it’s needed.
Get hold of someone with Cat ET and download a Product Status Report would be my first suggestion. Once you have that at least you know what you are dealing with. Do you have any idea if the operating software in the "bad" original ECM and in the replacement are the same.? There must be dozens of different C-12 on-hghiway engine software files out there depending on application. Not only BHP differences but it's quite probable that a software file for 375BHP in a Freighliner could be a different Part Number to one for 375BHP in a Peterbilt application.
Seems like you are in usual what we mechanics call “ever since you worked … “ state of mind. Whatever you described not necessarily ECM problems ( I would say mega unlikely) but a cluster or VECU problems. The air pressure warning have nothing to do with the engine, besides compressor being mounted and powered by it. And check engine might just have bulb burned out, or contacts bad. Check engine not lighting and engine not starting - usually means ECM not getting power or bad, it is obviously not your problem. Nige is right about ET, however - you’d want to start with Freightliner scan tool, or start checking things on the cluster.
My thought process is this - If the ECM is the ONLY thing (need OP to confirm that) that has been changed to go from a truck where all the panel warning lights worked to one where some of them don't, my first though would be the ECM for obvious reasons. As strange as it may sound different ECM software Part Numbers can be looking for the incoming signals for the same parameter on different Pins of connectors J1 & J2. I have come across this before. I would be wanting to eliminate the possibility of incorrect/incompatible software in the replacement ECM before moving forwards. To me that is the logical first step.
That very well might be, me myself had to send one of mine back 4 times, because of various reasons, mainly because of wrong software for my Meritor ESS transmission. But I have strong feeling that OP has some more cluster problems. Which is easier to check.
As far as I figured at that time, because my ECM was coming back very fast first 3 times - they don’t repair the ECM you sent them - they get one from the “pool”, that is already fixed, either already having a version of the software they think is right, or program the software they think is right - and send it back to you. If I on that they will mess up that bad I wouldn’t even tell them about ESS option, just the straight 10 speed transmission. We would be fine with that. First time as far as I figured they se r me super 10 software version, and next some Eaton 15 speed with shift assist ( or at least what they told me) they did t even know about Meritor ESS before my ECM showed up. So whatever you saying - is highly possible.
Thanks for all the help! Ended up being the warning bar indicator. IS-2 5002557 This caused the check engine light and turn indicators not to work.
Here ya go!!! Multiple offenders deluxe!
Guess i can thank the mechanic for welding on the truck. He also fried the ECU. I’m just praying it was just the ECU, crankshaft sensor and warning bar instrument affected …… what a mess..
It can also ruin your bearings. If he hooks up ground in the wrong place. One of my customer owns 3 Swedish made plate rollers. Two of them can roll 1” thick steel plates 10’ long. So when they finish rolling plate in to pipe - they have to weld a seam. So one of his workers was hooking up ground clamp to the machine, not the part. Fried expensive bearings, and rods on two hydraulic cylinders were looking like they were shot out by machine gun.
Now the full story comes out.............. I would give him the bill for the repairs without batting an eyelid.
Absolutely!!!!!
Let’s hope the damage was done just to these parts. Time will tell….. unfortunately
What was he welding and where was the ground clamp? Did he disconnect the battery or turn a master switch off? Welding can cause issues but not always. Repaired ECM might have caused a voltage spike to the warning bar indicator or indicator was on its last legs anyway. Glad it's fixed.
Definitely not close to where he was welding. Otherwise there wouldn’t be an issue
My friend works in Portugal, for hydraulic supply company. He mostly services ( rebuilds hydraulic pumps and motors) copper mines. One day he sent me a video, with huge 3 1/2 -4 inches DC arc discharge, between hydraulic pump fitting and some kind of a piece of steel structure close to the pump.
Well we don't know yet. Circuit boards and other things can go bad for other reasons than welding.
That’s what OP said.
I’ve seen things damaged in transmissions and axles by careless welding practices, good number of times.
We don't know if the battery was disconnected or anything else about the welding. Have heard the key needs to be on to fry the ECM or other electronics.
Everything was working fine on the truck including the ECU when dropped off. Truck ran perfect just the clutch went out and needed replacing. The transmission mount was messed up and needed welded. I’m not sure exactly where he placed his ground clamp as i wasn’t there. He did say he disconnected the batteries. You have a point about the warning bar with maybe the new ECU but it all occurred from an event that should have never happened. Just my thoughts. These were parts that were working when truck was dropped off. A simple clutch change shouldn’t have affected an ECU, crankshaft sensor and warning bar. I’m trying to be optimistic though and look at it as if I’ve got newer parts that hopefully will last a long time!
If the batteries were disconnected should take welding out of the question but it's hard to know what all went on at the repair shop. Maybe something happened when they were taking things apart and a ground or other wire was loosened or disconnected but made contact enough to cause a sudden voltage spike??
Do you think if the batteries are disconnected but the ECU is also grounded to the frame that it still couldn’t be affected? I’m not being sarcastic but my thoughts is there would still be a chance.
Maybe. On newer trucks they say to disconnect both battery cables and the ECM when doing any welding. Would think the ECM would have fuses that would blow to prevent damage. I have 94 Ford with an M11 and the ECM power wires from the batteries have fuses.
Agreed!!! Fuse would be a great idea!