What module powers or controls the power to the instrument cluster display?

[PatchManager]

I'm investigating a battery drain issue with my truck. When the battery drain is in progress with the truck off, I see that the instrument cluster display is on but only shows "PRNDM". None of the letters are highlighted in any way. So, the display seems to be powered, but it isn't receiving any input as expected since the truck is off.

What module powers or controls the power to the instrument cluster display?

The issue I see is that some module seems to wake up after the truck has been off for around 30 hours and continues to draw about 5 amps until the battery dies. It isn't repeatable, so it has been difficult to diagnose. The truck has been at the dealership for over a week now, but have made little progress is actually resolving the issue.

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[Buyer2021]

What module powers or controls the power to the instrument cluster display?

FWIW / FYI, looking at the 2022 workshop manual I find the following power inputs to the IPC (Instrument Panel Cluster)

• BCM fuse F13 (7.5A) which is noted as "Hot at all times"
• On the hybrid there's also shown BCM fuse F35 (5A) which is noted as "Hot in Start or Run"

I don't find anything specific to the "PRNDM" display within the IPC.

Looking at the transmission controls pages I don't see any direct link to the IPC, so suspect that "PRNDM" status is communicated from the tranny to the PCM > BCM > IPC via the CANBUS network (which 'talks' to all of these components via various paths).

Hope that helps, Good Luck!

 

[PatchManager]

FWIW / FYI, looking at the 2022 workshop manual I find the following power inputs to the IPC (Instrument Panel Cluster)

• BCM fuse F13 (7.5A) which is noted as "Hot at all times"
• On the hybrid there's also shown BCM fuse F35 (5A) which is noted as "Hot in Start or Run"

I don't find anything specific to the "PRNDM" display within the IPC.

Looking at the transmission controls pages I don't see any direct link to the IPC, so suspect that "PRNDM" status is communicated from the tranny to the PCM > BCM > IPC via the CANBUS network (which 'talks' to all of these components via various paths).

Hope that helps, Good Luck!

Thank you. That is helpful and gives me another item to check. It does seem interesting that it would require that much current.

 

[Buyer2021]

It does seem interesting that it would require that much current.

I only mentioned the fuse amp spec to aid with identification.

Note that both of those fuses also feed other modules, IMO the fuse amp-rating doesn't necessarily reflect any given module's normal power consumption.

Fuse amp-rating should be ultimately limited by the ampacity of the wires in the circuit, to prevent over-heating wire-failure / fire-risk in case of demand overload for whatever reason.

 

[Snakebitten]

Since the IPC module is what drives the actual Instrument Cluster panel, I'd assume it's awake for even lighting the smallest section of the panel. In this case, the gear selector position.

I also suspect it's backlit even if nothing else is being displayed?

Looking forward to what you witness with those fuses pulled.

 

[PatchManager]

Yes, the backlight is on to the whole display. It doesn't show that the truck is in park and the gear shift LED next to the "P" flashes. This may be happening because most of the truck is off, but a few things are powered and not getting the expected input.

I'm now thinking that it would have been more productive for me to do more diagnosis before taking it to the dealership.

 

[Buyer2021]

I'm now thinking that it would have been more productive for me to do more diagnosis before taking it to the dealership.

Ah, well, hindsight is always great, eh?

Attached just FYI, Battery Drain Check procedure from the 2022 workshop manual.

A quick scan indicates the comprehensive procedure might be labor-time intensive ($$ for a dealer if not covered by warranty) but mostly do-able for a patient DIY-er with a fairly inexpensive low-current DC ammeter.

I hope your dealer finds something that makes their effort warranty-eligible

Good Luck!

 

[PatchManager]

Ah, well, hindsight is always great, eh?

Attached just FYI, Battery Drain Check procedure from the 2022 workshop manual.

A quick scan indicates the comprehensive procedure might be labor-time intensive ($$ for a dealer if not covered by warranty) but mostly do-able for a patient DIY-er with a fairly inexpensive low-current DC ammeter.

I hope your dealer finds something that makes their effort warranty-eligible

Good Luck!

Thank you for the attachment and for your research. I really appreciate it. I am getting the truck back today for a few days, so I will be able to try a few things over the weekend. I have pretty good information at this point that the truck draws about 5 amps when it goes into battery drain mode. Due to my profession, I have some nice tools for troubleshooting current draw issues. At the same time, I'm a mediocre mechanic at best. I do think that if I'm going to get this problem resolved, I'm going to have to do much of the diagnosis myself.

 

[Buyer2021]

Thank you .....

You're quite welcome, wishing you the best of luck!

 

[PatchManager]

I got my truck back on Friday to use it over the weekend. After using it all day Saturday, I found the battery was very low by Sunday morning, so I connected a battery charger. Charging the battery when it is in this battery drain state keeps the battery from dying, but the truck remains in the battery drain state. I found the current drain was approximately 3.3 to 4 amps using a clamp meter, so I started pulling fuses in the BCM fuse box as noted in the attachment @Buyer2021 provided. After pulling fuse 32 (audio control module) and fuse 13 (instrument cluster and steering column control module), the drain current dropped from 3.3 amps to 30 mA. Once I plugged them back in, the truck was no longer in the power drain state after the truck went into "sleep" mode.

It seems clear that the current draw is due to the ACM and IPC. However, item 14 in the Ford procedure states:

14. If excessive current draw is isolated to a specific module, verify if a module input is the cause of the concern. Refer to the corresponding workshop manual system operation and component description section to determine the inputs (hardwired or network messages) received by the module in question.

I think this means the module drawing the current could be doing so because it is bad or because another module is waking it up -- "verify if a module input is the cause of the concern". I don't know how to test this. However, it seems to me that if another module is the cause of the ACM waking up, the current draw with the two fuses removed would be higher because the module waking up the ACM/IPC would be drawing current.

My current thought (speculation) is that the ACM is the issue and the instrument cluster module is waking up due to some input from the ACM. I think this because I removed the fuse for the IPC and the current draw dropped, but didn't go to milliamps. When I removed the ACM fuse with the IPC fuse already removed, the draw dropped to milliamps. One problem that I ran into was that the ACM fuse had to be removed for many seconds to see that the current draw drop to milliamps. If I have another opportunity, I will only remove the ACM fuse, let it sit for a period of time, and then see if the instrument cluster powers back off.

Any thoughts you have or further steps to diagnose this issue would be appreciated. I have a few other experiments to try the next time the truck goes into the power drain state.

 

[Buyer2021]

After pulling fuse 32 (audio control module) and fuse 13 (instrument cluster and steering column control module), the drain current dropped from 3.3 amps to 30 mA.

Just curious, what was the incremental drop for each of those individual fuses / modules?

Did you wait for the truck to go into 'fully passive' / 'resting-state' between each fuse-pull measurement (suspect that could take 15-minutes or more with nothing being touched on the truck and no fobs in the vicinity)?

 

[PatchManager]

I wasn't as methodical as I should have been, but this was my first go around. After I had removed around 20 fuses with no perceptible change (current draw, sound of any kind, lights, etc.), I was not allowing much time between removing a fuse and removing the next. The instructions did not indicate a delay between fuses was needed. When I removed fuse 13, the current dropped by about 600 mA from ~3.4 amps to ~2.8 amps. I then removed fuse 32 and it dropped to ~30 mA after about 20 seconds. I accidently waited after removing the fuse. When I replaced fuse 13, the truck made a number of noises with a clunk and what sounded like a electric motor running for a few seconds. The next time the truck goes into the battery drain state, I will remove one, wait a period of time, re-insert it, remove the other and then wait a period of time.

 

[PatchManager]

After a few more dead batteries and more analysis, I have found that removing fuse 91 (trailer tow light module) from under the hood stops the battery drain and the other odd problems I see. I think the other fuses I removed were related, but not the root cause. I discovered this when I rented a trailer last weekend and received a number of faults. When checking into the trailer faults, I discovered fuse 91.

Could someone (@Buyer2021 ?) please provide a wire diagram associate with fuse 91? I would like to unplug related components to see if I can narrow down the issue.

 

[Tired Lizard]

I don't know the year, one of the service / shop diagrams found on the site.

TRM Fuses. BCMC F91 C1035B p15 -- C1590 p15 -- C2498F p14 -> TRM.

F91 powers the unit - this is what creates the Left Signal, Right Signal, and Parking Lights
F107 feed goes to an internal relay and out on the Orange wire (battery charge connection).
F42 = TT Electric Brake.

 

[Buyer2021]

Could someone (@Buyer2021 ?) please provide a wire diagram associate with fuse 91?

FYI, one has to go through individual drop-down menus under Power Distribution in the wiring diagrams to find these things, this is on page 111 of 133 ...

While ^there^ I grabbed to following using the hyperlinks on that page

Hope that helps, Good Luck!

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