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Discussion Starter · #1 · (Edited)
Here is a summary of my findings. In addition, it appears it sits between the charging port and the on board battery charger for the pilot wire connection.

(Located under the front passenger seat)
The hybrid powertrain control module 2 has many functions:
monitoring the hood latch
sends the bcm a signal to honk horn during plug in
charge door/fuel door functions
fuel tank pressure before filling
sends pwm signals to cooling fans (pass through from ecm)
gathers reading from ambient air temperature sensor
controls a/c compressor speed based on other sensor inputs (like battery temp)
controls passenger heater core valve
controls high-voltage contactor relays
controls 14 v power module vent fan
battery pack coolant pump
receives faults from on board battery charger
calculates battery performance
works with battery charger for cell balancing
modifies the control pilot signal
time of day charging feature
monitors input/output of on board charger
evse cable attached check (proximity detection)
 

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HPCM2 is essentially the most important module in the Volt's management system as (as you've listed) it integrates with so many systems and activities. It is located under the right front passenger seat and If you move the seat all the way back and flip up the small carpet cutout you can easily access it.

FYI the HPCM2 does not directly connect to the on-board charging module as you (or the LEAR document) suggest. That module shown is actually something only LEAR utilizes for bench calibration. It is not HPCM2 or even one of the modules in the Volt.
The HPCM2 communicates with the OBCM (and other modules) via the GMLAN network (SWCAN) used in the Volt
HTH
WOT
 

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Discussion Starter · #4 · (Edited)
WopOnTour, do you know if a "Pilot Level Fault" or failed diode test on the EVSE would trace back to the in-car-charger? I just replaced my in-car-charger and 5 different blink public stations give me the pilot level fault error. My openevse works fine.
This link has be thinking the diode might be somewhere between the in-car-charger and the j1772 port:
http://gm-volt.com/forum/showthread.php?146897-Volt-Failing-EVSE-quot-Pilot-Diode-quot-Check-%28Won-t-Charge%29&highlight=hybrid+powertrain+control+module
 

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Discussion Starter · #5 ·
Also, how could the HPCM2 modify the Pilot signal from the charger? See what i'm talking about on page 4591 in the 2012 service manual.
 

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On the Volt the on-board charger itself isn't really involved in the pilot signal.
HPCM2 is the primary interface for both the pilot and proximity signals.
If you look on the charging system wiring schematic on the very last page of the PDF you posted above, that should be clear.
The 2 AC mains, and ground are the only circuits on the plug-in receptacle that are hard-wire connected to the on-board charger.
So yes, the HPCM2 could be the root cause of almost any pilot circuit condition.
WOT
 

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Discussion Starter · #7 ·
Thank you very much! From what I understand a HPCM2 replacement will require dealer programming or some kind of initialization. Is this correct?
 

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Thank you very much! From what I understand a HPCM2 replacement will require dealer programming or some kind of initialization. Is this correct?
Yes, it is programmed once installed into the car via the under-dash data link connector (DLC) using a special interface (MDI) and TIS2WEB (a GM application available on GM GLobalConnect)
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Discussion Starter · #10 ·
I talked to Drew Technologies about initializing a second hand HPCM2. They mentioned the volt utilizes GDS2, but were not sure if this swap would work. Do we know if these modules can be reflashed for a different car?
 

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Discussion Starter · #11 ·
No answer to the above question yet, but I did order a new hybrid powertrain control module 2 and it fixed my charging problem. Here is what I discovered.

Installed the new hpcm2 and turned the car on just to see what would happen. Several lights stayed on, icy road warning popped up, and the car stayed on the initializing screen for several seconds. Once complete, the car would not move, but would allow me to shift out of park. I installed the old hpcm2 and drove to my
...drum roll....
Local GMC dealer! for programming. And yes, they did program/initialize it! No local "Chevy" dealership would even attempt to work on my car.

After an hour of programming I paid the $105 fee, went home, and my car was able to charge again. My lifetime MPG was reset, but oil life % did not get affected.
 

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No answer to the above question yet, but I did order a new hybrid powertrain control module 2 and it fixed my charging problem. Here is what I discovered.

Installed the new hpcm2 and turned the car on just to see what would happen. Several lights stayed on, icy road warning popped up, and the car stayed on the initializing screen for several seconds. Once complete, the car would not move, but would allow me to shift out of park. I installed the old hpcm2 and drove to my
...drum roll....
Local GMC dealer! for programming. And yes, they did program/initialize it! No local "Chevy" dealership would even attempt to work on my car.

After an hour of programming I paid the $105 fee, went home, and my car was able to charge again. My lifetime MPG was reset, but oil life % did not get affected.
Told ya! lol ;)
No Volt dealers in your area? I'm surprised to hear you had so munch trouble finding a dealer to reflash it.

Yes it would be normal for the lifetime mpg average to be reset after programming HPCM2 as it is both processed and stored in HPCM2. The oil life index all is in the ECM.
In any case you're fixed!
enjoy!
WOT
 

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Anybody have a best guess as to what the root cause of the HPCM2 failures may be?

Mine was fried and it took 19 days for the dealer to figure out what happened.

I have a sneaking suspicion it might have something to do with a weird spike that came out of the GE-brand Level 2 EVSE the car was plugged into before I started experiencing pilot signal error codes...
 

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I just went in for CEL issue (code P1EE6). The dealer said they had to update my BECM and HPCM2 per a bulletin referencing that code.
Claim code BECM K16 CDF04-HPCM2 1C114 c13a04 (What ever that means)
My lifetime mpg didn't change
2013 Volt
 

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Anybody have a best guess as to what the root cause of the HPCM2 failures may be?

Mine was fried and it took 19 days for the dealer to figure out what happened.

I have a sneaking suspicion it might have something to do with a weird spike that came out of the GE-brand Level 2 EVSE the car was plugged into before I started experiencing pilot signal error codes...
There's nothing chronic AFAIK.
As far as I am aware this HPCM2 unit is the only one we've heard on gm-volt.com being replaced.

WOT
 

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Glad the problem is fixed. I ha a similar issue 3 years ago that was resolved with a GM firmware update.

Interesting information from the Lear Charger unit description: Efficieny is 91.7% in L2 and 90.6% in L1. So in theory 110V charging is 1% less efficient than L2. We observe that a full charge takes ~13kW for ~10.5kW of delivered power, which means 20% charge loss: ~8% of the energy loss is in the charger and ~12% in the battery itself. That 20% loss is quite significant: 8000 EV miles that I lost to heat until now.....

I am still experiencing that the GFCI circuit breaker trips almost daily while charging L2 here at work. A colleague with a Toyota Rav 4 EV who uses the same upgraded Nissan EVSE has the same problem: it pops somewhere during the first hour of charge, and doesn't pop once the GFCI is reset.

The electrician here measured charging current: 16A with is correct well within the 20A limit. The Lear charger description says that drawn power will never exceed 3.3kW (16A). So that leaves a ground fault as a possible culprit, most likely in the Nisan Charger. But why does it not always pop, and why this in this pattern? That does not make sense.

Anyway, I have been living with this issue for the past 3 years and 40K EV miles. Its good exercise to run back to the parking lot to reset the breaker each day.
 
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