P0218 low fluid?

Cougar281

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Sep 11, 2006
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Thanks but there is no EBCM or BCM
Well, that would explain why it's complaining about a loss of communication with the EBCM and BCM. Could still be something wrong with the GMLAN bus... Did you ever get the termination sorted out?

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Mogman

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I have no idea if it has GMLAN, it has a serial communications link between the DLC, ECM, TCM and TCCM, I have jumped it at the glow plug controller (and have tried it with the controller in place), the guy that made the stand alone harness eliminated all the rest, I can read and write (including a few full flashes) to the ECM with no issues, I can read the TCM, have not committed a license yet as I am waiting on another TCM to arrive.

I have read several post around the web stating that a defective TCM can cause these kinds of issues, it only had the termination in the ECM but I have tried 1 and even 2 120 ohm terminations with no change in the symptoms, I mean it is only two wires, and there does not appear to be any short to ground.

I am not saying it cannot be in the harness but I have been all over that thing and cannot find an issue. Also the issue gets worse the longer the engine is run and the modules get hotter (more codes) and I have confirmed the trans temp resistance and voltage is good dispite that the TCM is reporting high temp, the TCM MIGHT be here tomorrow, USPS has done their best to make it as slow as possible the 2-3 day priority package has been in the system for almost 12 days now.. I have a 2008 (same year) 1 ton but have fought the urge to swap modules......

Also I did program it as a stand alone without the Allison and all I got were a couple what turned out to be legit engine codes which have now been resolved.

The ECM does have a fairly good dent in it from the donors wreck so I am also not discounting that possibility although it has not shown any problems, ALL the codes I have now are reported as TCM generated codes, if the TCM does not fix the issue I may swap ECMs as I have already committed a licenses to each of them....

Also when the TCCM is powered up it sends a code because the shift motor is evidently bad and am waiting on that part also so it is apparent the serial link is not severed as in a missing module or a missing module that needs to be jumped
 
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Mogman

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Yep this is starting to get annoying, the TCM came in today and same thing, well one thing I noticed is the first time I cleared the codes I had a large number of ECM codes starting with P0102, the second time I cleared the codes I get the usual U0140, this is defiantly set to "not reported, no MIL" also a U0121 which I have not found in the tune and also P0880, no doubt would get more if I took it out for a drive.
So I am at a total loss, maybe it is power related, I think ALL power is switched by relays, I did find a diagram (plug view) of power and grounds to the TCM and they seemed to check out fine (with ign on), and here I thought stuffing a Dmax into a Humvee was going to be the hard part...........

question is it OK that all power is switched or is there any power that must be to the modules 24-7? is so what pins on what modules?
It seems if you must wait after turning off the ignition when programming the ECM that it must have power to be doing something......
 
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Mikey52

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Sep 20, 2018
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The ecm and a few other modules are typically still awake for a time after you turn the key off. They each go to sleep at predetermined settings.
 
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Mogman

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OK I had made a mistake and had pins 10 and 70 on a switched circuit, I have it going directly to the battery now along with pin 77 on the ECM and double checked all grounds etc.

So I cleared the codes and went for a test drive twice, once with each TCM and the results are the same, no power, transmission is shifting (with a little coaxing by lifting the accelerator), max 45MPH and both times when I returned I had a U0140, U0121 and a P2536 codes.

So at least things are getting more stable and the P0880 and U0073 (Bus off) and all the other codes are not present any more.

As far as the P2536 I get two different items when searching one says TCM power issue and one says acc key position, I did not get any leads marked ACC on my stand alone harness so I am assuming at this time it is the TCM power error code....

EDIT, maybe time to see if someone would look at my tune to see if I have missed something, but I swear I have U0140 set to "not reported, no mil" and cannot find U0121 or P2536 in the tune
 
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2004LB7

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Found this from another site about P2536

Circuit/System Testing

1 Ignition OFF, disconnect the harness connector at the TCM.

2 Ignition ACCESSORY, test for greater than 5 V on the signal circuit between the TCM harness connector terminal 43 and ground.

¤ If less than the specified value, test the signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the BCM.

3 If the signal circuit tests normal, replace the TCM
 
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Mogman

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Found this from another site about P2536

Circuit/System Testing

1 Ignition OFF, disconnect the harness connector at the TCM.

2 Ignition ACCESSORY, test for greater than 5 V on the signal circuit between the TCM harness connector terminal 43 and ground.

¤ If less than the specified value, test the signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the BCM.

3 If the signal circuit tests normal, replace the TCM
OK that is interesting, there is no connection between ACCESSORY and the stand alone harness, only run (ignition),, battery and start, I see accessory wake-up serial data pin but where do I connect the ACCESSORY lead to the stand alone harness or modules? (EDIT considering the signal should come from the BCM which is no longer there) I will go out in the am and look at that pin but doubt there will be anything there as when I switch to ACC nothing should happen on the stand alone harness as wired.
ALSO, THANK you very much for taking the time to help me with this, it is about to drive me bananas!!!!!!

EDIT OK I missed the fact the TCM is unplugged, so with no BCM there will be no accessory wakeup signal possible, so if that is what is giving me the P2536 than it has to be tuned out or I need to supply 5V (or greater than 5V) from somewhere......

EDIT2, there is zero volts on pin 43 in any ignition switch position, HUMMM!!

I wonder if I should delete P0700 TCM requested MIL illumination
 
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Mogman

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I received a message from someone from the EFILive forum saying that the wakeup lead on both the ECM and TCM should be tied to the IGN. leads so we will give that a shot today.
 

Mogman

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Found this from another site about P2536

Circuit/System Testing

1 Ignition OFF, disconnect the harness connector at the TCM.

2 Ignition ACCESSORY, test for greater than 5 V on the signal circuit between the TCM harness connector terminal 43 and ground.

¤ If less than the specified value, test the signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the BCM.

3 If the signal circuit tests normal, replace the TCM
You were definitely on to something there, I have connected the "wakeup" pins on both the TCM and ECM to "ignition" and the P2536 code is gone, I am still getting the U0140 and U0121 and still have LOW engine power
 

2004LB7

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I don't know if this thread will help for U0121
 
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Mogman

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I don't know if this thread will help for U0121
Thanks, I think it is time for a new thread as the problem is different than what I started with, as I have resolved the first complaint, Thank you for helping me with this!!!!
 

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