Waiting on TCU 3G to 4G "upgrade" from Ford - 2016 C-MAX Energi car won't start

[Amanda]

Hi everyone,

 

I'm trying to help my mother in law get back into her car. 2016 C-Max Energi. It has been at the dealership for nearly 5 months waiting for Ford to make the part she needs. Q4 2022 came and went and now they want her to take the car back because it is taking space on the lot and they don't know when/if a part (Telematic Communications Unit) will be available.

 

After digging around the forums, reddit, and anything else I can find. Here is what I think I know. I would love any guidance y'all can provide on the bullets below. Most importantly I want her to be able to drive her car with confidence. We really don't care about all the bells and whistles at this point.

 

• Ford has known issues with 3G/4G and releases a TCU upgrade for a lot of models but unfortunately with the C-MAX it doesn't work. They go back to the drawing board and a year later there is still no solution. https://static.nhtsa.gov/odi/tsbs/2021/MC-10204043-0001.pdf 
• I don't really know what the TCU does but I did see in one of the threads that it isn't required. https://fordcmaxhybridforum.com/topic/14268-tcu-module-power-drain-affects-power-steering/?tab=comments#comment-87268 I would love to know more about how to "bypass" if that is an option. While it would be nice to have all the features of the vehicle, at this point all she needs is a car that gets from point A to B. 
• Reading through other owner's issues I see C-MAX has had lots of problems over the years (power steering, radio, battery, etc) - they all seem to have the common issue of "battery drain." A lot of the stuff is dated and my guess is there is a troubleshooting guide somewhere or perhaps someone here that can help me go through a few diagnostic tests and or known fixes for common things. I'm willing to pull fuses or ask for software updates if I know what to ask for. 
• I'm also willing to just keep the car on a trickle charger for the next 6 months if that will help. Have her keep jumper cables or a battery jump starter in the trunk. Anything really to get her back into her car. 

 

Questions:

1) Before we get the car back from the dealer is there anything we should be asking them? Specific diagnostics run, results, error codes? 

2) Are there any resources OTHER than the dealer. Perhaps someone who might be able to help and is within 2 hours of Los Angeles?

 

Thank you!

 

- Amanda 

 

Edited January 3, 2023 by Amanda

[SnowStorm]

I don't have an Energi model and have no experience with the TCU but here are my thoughts based on the understanding that the car has a 12V battery drain

problem somewhere.

• There could be a drain somewhere else - replacing the TCU wouldn't help.  The dealer may not know about it, simply sees that the TCU is out of date so says you should replace it.
• You should find out exactly what is happening with the 12V battery over time.  Get a voltmeter and a jump starter (the small lithium-ion ones are great).  Use the 12V "jump-start" posts under the hood on the driver's side.  (You can also plug the voltmeter into the 12V jack in the back since it doesn't turn off.)  When the car is ON (Ready-To-Run), you should have over 13VDC - the 12V battery is being charged by the DC-DC converter.  When the car is OFF the voltage will be below about 12.8 volts.  Check the voltage with the car OFF, first in the evening and again in the morning.  If there is a drain, it will go down a lot.  A 12V battery is considered fully discharged at 10.5 volts but it might go a lot lower than that and the car will still turn ON.  I've seen mine down around 4 volts!  Of course at that point you have to use the jump starter.
• You should have the 12V battery load tested and replaced if it fails.  (Be sure the mechanic knows how to reset the battery age counter.)  You still need to perform the above step or you may end up eventually ruining the new battery.  Repeated discharges of the battery to a low level will damage it.
• Can't the TCU be simply unplugged if it is the culprit?  I understand its no good anyway with 3G dead.
• You can also get the Forscan software and a compatible OBDII adapter and investigate lots of codes and issues that way if you want to get into the guts of everything.
• I would think using a trickle charger should also keep you operational but still keep the jump-starter in the car when away from home.

[cr08]

On 1/18/2023 at 9:07 AM, SnowStorm said:

Can't the TCU be simply unplugged if it is the culprit?  I understand its no good anyway with 3G dead.

 

The TCU is still needed for Value Charging and Go Times features to function if those are in use. This remains the case with the old 3G modems and no cell service.

 

While they can be unplugged, it is a royal pain to get to. It's behind the driver side trim panel in the cargo area in the back and requires taking out almost all of the trim panels in the cargo area to get that far. It's also shared with the same fuse as the APIM so removing that will disable the APIM as well.

 

From what I have seen on various boards, there have been zero mentions of any abnormal 12v battery drain issues after the 3G shutdown or any relation to the TCU as such so at best I'd ignore that as a potential culprit except if everything else has been ruled out first.

[jzchen]

I'm sorry to read of your issue just now.  (I had been out of the country, then had a tiny break, then at a field trip basically as a taxi for students).  Ours was a '13 and had battery drain issues, or at least a TSB that wrapped the harness to the trunk lid as well as programming.  Interestingly ours and another person on here actually had both our 12 V batteries die on the same day at around the same time and in almost the same vicinity, (in Orange County, CA).  I suspect some sort of signal from Ford woke our cars up and eventually drained the battery.  (I don't believe that it was a coincidence).  I bought a T5 replacement (if I remember correctly) at the time.

 

I know of no specific tests to run.  Just clarify that any open recalls or such have been completed on the car, or at least parts on order.

I am in the San Gabriel valley and should still have my old cable that I got to use ForScan.  If you run into trouble you can PM me and maybe I can take a look....

 

I would advise buying a portable jump pack and keep it fully charged.  Then hopefully if it is found dead connect it to the underhood jump points and start it up to get going.  (Make sure the jump pack you buy can reach the + and - points, or + and something solid for the -.   

[Stlouieray]

I have a 2016 CMax Energi, and I do have a battery drain problem.  My car has been at the local Dealership for over a month.  When I first took it in, they replaced the battery and said "You had a dead battery."  Ten days later, my car dropped dead again, but thankfully, in my own driveway.  I took the car back in, and they replaced the battery saying "Well, apparently, you just had a bad cell in the battery so, we put a new one in . . . you should be good to go."  Guess what happened a week to ten days later?  Same freakin issue.  So, I took my car back, and they kept it in their service area, trying to decipher where in the heck the battery drain was occurring.  Initially, they couldn't find anything, and I was so angry asking them "Are you people even calling the Ford Motor Co. Engineers, to make an informed diagnosis?"  Well, after about ten days of sitting in their garage again they said 'We think we've isolated the problem, and it's in a 3G Module."  Anyway, it's been a month now, and my vehicle is still sitting in their service garage, and as far as the replacement 4G Module, they don't know when they can get one in.  But I've had the same feelings as such:  When/if this part does service, was that the real issue for the battery constantly draining over a period of 7-10 days?  I need some help, somewhere, but it's not coming from the Manufacturer, or the Dealership.  Can I write to someone at Ford Motor Co.  I can't find email addresses, or the typical email format that each employee uses, but someone like Elena Ford would be a good candidate.

[Hfly1]

Not sure if the OP has found resolution. Check this CSP update out: https://static.nhtsa.gov/odi/tsbs/2022/MC-10216851-0001.pdf

I have a 2016 C-max Energi that I bought the 4G modem kit in Jan. 2022 (18 months ago) and the service center still refuses to install it. My car does not have any noticeable battery drain unless I sit with the accessory power on for a long time. That will drain the 12v. The work around is to turn the car all the way on (pressing the brake when turning it on) to engage the high voltage pack. That keeps the 12 v charging even while sitting. The car still drives fine without the still installed 3G TCU functioning.  After having the car sit so long unused I would make sure the 12v battery is not completely dead. I would also ask the service center if there is a way to query the status of the high voltage cells. First thing I’d do at home is charge the car. Then I would keep driving it and keep bugging Ford and the  service center about the CSP.