"check engine" light 4 days after installation

If it was a transient problem, four reboots tends to clear the
triangle and check-engine light. That may be what you saw.
A good scanner may still be able to pull what happened as a
"history code", so worth trying anyways.
.
My first guess would be a CAN glitch, which might give you
a U code of some sort.
.
_H*

 

I have experienced this a number of times on really cold mornings and only after charging for extended duration - I can start the car all day after getting pack going initially and the problem wont recur.

Here's my cureall for the red triangle at wake up - start up,
1) Start vehicle - if engine starts up IMMEDIATELY - then it is in limp mode. Turn off - Restart.
2) The second start always starts up normally but still shows the fault.
3) Wait 5 seconds, cycle the on-off switch - the triangle will likely flicker once or twice
4) Repeat the process after another 5 seconds.
5) Done.

There is likely not a problem with the fundamental operation of your pack - perhaps there is some kind of software update that will come to fix the annoyance.

I am guessing this is some kind of CAN sync'ing issue right at start up - why on cold mornings - not sure. 12V battery is perfect - no problems there.

 

When I had my install done last week, the tech plugged in a special laptop and did a number of software-related checks, including checking the software revision (I have the latest). He said he could update the software if I didn't - perhaps this might have something to do with the intermittent red triangle? Just a thought...

 

I had my Hymotion system installed about a month ago. After the first few days, I started seeing the big red triangle and the check engine light. In my case, the problem usually occurred after my pack was completely discharged. It seemed to occur at random times.

A123 Systems eventually replaced my unit with a new one.

I wouldn't drive a Prius when the red triangle or engine light are displayed.

The Hymotion manual explains how to clear this kind of error:

"Resetting communications between the L5 PCM and Prius
​

Some temporary and minor problems could be resolved ​

​

​

​

by resetting and saving the Prius' communication and
diagnostic codes. This is done by turning the vehicle off and on five times, pausing aminimum of thirty seconds​

between cycles."

If the error recurs, you should probably disconnect it. In the back corner of the car, on the left side of the battery, there is a big white connector. Disconnect it and connect it to the identical connector (with jumper wires on it) that is hanging next to it. This completely disengages the Hymotion system from your Prius and allows your Prius to operate as it normally did before the battery was installed.

I would suggest that you either call A123 at 508-497-7398 or call the dealer where your battery was installed.

They will probably ask you how many times the red LED (on your dash) is flashing. It flashes a different number of times for different errors. Mine was doing 11 short flashes, followed by on long flash, and then repeating.

I hope this helps.

Arthur

 

Fixed it - my 12V was dead dead dead. As soon as I put a battery tender on overnight the problems dissapeared. I checked current draw on the 12V when charging and couldn't see any difference - so I don't think the A123 Battery is killing it.

I repeated some tests over the weekend to check at what voltage the system starts to register errors - red triangle. Looks like about 11.5 V - drops to 9.5 V when everything starts sucking juice - my 12V battery is definately toast.

On the cold mornings - 29 - 32 F approx - we've been having lately - my 12V is dumping to 9.5 V before load applied and the car won't even start - so I had to bypass the PCM with the bridge plug and after the car has put some charge into the 12V - change back to PCM harness - everything boots up ok and runs normal.

Soooo - I guess I need a new 12V battery - but I'd like a way to make sure it doesn't continue being a problem. That little bugger has been a source of pain - though it seems to affect the PCM before it affects the car .. need a high capacity replacement - or a battery tender - since I am plugging in anyway - should have a little 12V charger running to the battery to keep it topped off .. thoughts.

I sent off some e-mails to the A123 systems gang - see what comes back.

 

Great observation. I have not had this worry since my Prius is brand new. I'm sure this could help others with older 12v batteries. With winter close I think a new 12v battery would be due. I'd be curious with a123's reply. Since hymotion started in Canada I would expect that they would have experience 12v battery issues by now.
Chris

 

Correct...restarting the car 5X clears the cann bus faults.

Hybrad