Allison Transmission Fault Code SPN 2003 FMI 31 (2024)

It seems that all Allison fault codes begin with a P. At least they do with the 1000 and 2000 series transmissions. This change makes it hard to find the real problem. One mechanic needed the MID number to get to the real source of trouble.

After some research, the SPN 2003 FMI 31 code may be relegated to the Blue Bird Buses that have been made prior to 2016 approx. That is the most recent date we found. It is telling you to change the trans spin on the filter and then use the reset process to clear the code.

To learn more about this code and what it means, just continue to read our article. It explores the issue to make sure you have the best information possible. We do the research so you do not have to waste time looking things up for yourself.

SPN 2003 FMI 31

Freightliner Code SPN 2003 FMI 31

More on The SPN 2003 FMI 31 Code

Allison Fault Code SPN 2003 FMI 31

We have given you one explanation for this code and there is another one. The code may be different since the transmissions are not all installed in Blue Bird buses. Here is what one mechanic and another website had to say:

SPN 2003 is a diagnostic trouble code for bad connection between ECM and TCM” The mechanic stated to the person asking him what this code meant that he needed the MID code to make a correct diagnosis.

On the vehicle in question, the MID code was 3. First, he explained that the 31 was a generic code that is generated by the ECM. The 2003 gives the actual location of the problem which is the TCM.

With the information from the website, this code is telling you that there is a connection problem between the two control modules. There are two fixes for this code.

1. Remove the harness connecting the ECM to the TCM and then check it for damage. If it is, then you would have to replace the harness. But if it isn’t then you need to remove the harness, then put it back on to make sure the connection is sure.

2. You do this because the second source is a faulty TCM. So you put the harness back on and check to see if the code clears. If it does, then you are fine. If it doesn’t, then you need to remove the TCM and have it tested.

Replacement is probably your only option to solve the problem if it is a faulty TCM.

DTC J1939 SA 3 SPN 2003 FMI 31

Allison Transmission Fault Code SPN 2003 FMI 31 (1)

What would make fault codes easier to understand is if they implemented a universal system that applied to all engines and other automotive parts.

As it stands, finding out what is wrong can be difficult as sometimes even mechanics and dealers do not know what the fault code stands for. In the case of the Blue Bird Bus situation, it was a J1939 communication code fault.

The fix for the Blue Bird bus is to replace the trans spin-on filter on the 2010 model. The 2011 IC BE model has the same fix but it was called the Trans oil filter restriction switch.

The fix also worked on the 2011 RE and the 2016 IC. After replacing the switch or the trans spin, you need to use the reset code to clear the fault code. What you do is turn the ignition on while leaving the engine off. Then use the shifter to do the following- N-D-N-D-N-R-N.

That should reset everything and you should be good to go. This process also worked on resetting the pm service interval. We looked at the complete Allison fault codes list and there are only 2 times where the TCM is mentioned:

P0602 for the TCM not being programmed and P1760 which is the TCM supply voltage. You can read this list at this link.

Freightliner Code SPN 2003 FMI 31

Allison Transmission Fault Code SPN 2003 FMI 31 (2)

We looked at the Freightliner code list and there were several J1939 codes listed. One was for the FMI code and 31 just says ‘condition exists’. As the mechanic said earlier, it is a very generic code and doesn’t tell you much.

The first of about 5 or 6 J1929 codes have the SPN 2003 number. But it is not that informative either as all it says is- Missing Transmission CAN Message. Then it lists 1 possible FMI code number and that was 9.

All FMI 9 states with the 2003 SPN is an abnormal update rate. However, all the experts we came across outside of the Blue Bird bus response point to the ECM to TCM harness.

We described the fix and that fix, unless otherwise discovered, applies to the Freightliner engines as well. You can read those codes at this link. Do the easy repair first, simply remove the harness and put it back on securely.

If that doesn't fix the problem, then move on to the other option and have your TCM checked out.

More on The SPN 2003 FMI 31 Code

Allison Transmission Fault Code SPN 2003 FMI 31 (3)

There is a little more information that needs to be reported. First off. 99% of the time when you see this code the TCM has to be replaced. No questions asked. But the full code for this issue for the 1000 & 2000 Allison transmission series is:

ECM: Allison - 1000 & 2000

Fault: P0614

SPN: 2003

FMI: 31

This code usually sets with the code P2637 or code P2641. The presence of those codes tells you that the Autoselect is still functioning and it is a software issue.

Some Final Words

It would be a great automotive world if all automotive parts like engines, transmissions, etc., used the same codes. But since it is not a perfect automotive world, it takes time to find what different codes mean for a specific part.

But given enough time, you should be able to find all the meanings of the codes and which parts they refer to.

Allison Transmission Fault Code SPN 2003 FMI 31 (2024)
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