Battery pack fan circuit issues

[crx_rogus]

Folks -

I appear to have damaged the pack fan driver circuit enough to cause a second 1644 code. First, I fed reverse 6V to the circuit while grid charging, leading to the first 1644 episode. Eventually, with the charger circuit completely disconnected (4-pin Molex for pack + fan leads), the code would stay away, but voltage to the fan became unreliable, so I provided resistor-reduced voltage from the dash's 12V outlet to the fan. I must have switched around one of the wire spans because the charger's fan driver then fed the wrong polarity to the fan again (without changing anything with the charger assembly), which is probably what has led to this 2nd 1644 error code... which stays with the charger completely disconnected.

I ordered an electrical troubleshooting manual, should be arriving in a couple days.

So, if I have thoroughly broken the BCM, where would be a good source for a replacement? Hondaparts.com doesn't list it as available... It's part #19 in the related diagram, and the parts list skips from 18 to 20. (The MCM lists at $834.30.)

Any other ideas (besides the obvious "stop sloppily messing with an exotic cult car!")?

TIA,
Roger
'2000 silver 5spd #4047
63mpg w/ IMA, about 55 w/o
72mpg for about 10 miles after grid recharging

[uhtrinity]

I don't remember if this is the same code I occasionally get. It happens sometimes if I turn on the car when I have my charger plugged in AND the battery temp is over 90F which means the car is driving the fans. I have a 9v 3A power brick that runs on regular line voltage when the charger is connected. This brick is setup to drive the fans on the packs and is diode isolated so no voltage comes from the cars fan drive to the brick. I only see this on the rare occasion I forget to unplug the car when rolling up the windows and it usually clears itself. Worst case, I clear the code using my OBDII reader.

[crx_rogus]

Originally Posted by uhtrinity

I don't remember if this is the same code I occasionally get. It happens sometimes if I turn on the car when I have my charger plugged in AND the battery temp is over 90F which means the car is driving the fans.

That fits the conditions it happened under.

Originally Posted by uhtrinity

I have a 9v 3A power brick that runs on regular line voltage when the charger is connected. This brick is setup to drive the fans on the packs and is diode isolated so no voltage comes from the cars fan drive to the brick.

Essentially same setup as mine, but 6V/2A recently very temporarily hooked up backwards, twice now. When I last measured the voltage going to the fan from the car, it was 3.0 - 3.5V reversed polarity, never increasing. With the fan's connector reversed to try to get that 3.5V to actually turn the fan, the voltage dipped to a useless 1.8V, hence my assumption that the fan power supply has serious issues. That's what led me to, for the time being, use resistor-dropped voltage from the 12V outlet to run the fan motor. With that connected correctly, running the fan motor (connector un-flipped), the power to the outlet dipped a few times when I turned the accessory power on, which makes little obvious sense since it was the correct polarity to turn the fan, but that possibly contributed to this latest 1644. Having accessory power on for a bit with the charger fan driver sending opposite polarity voltage to the fan probably didn't help either... a bit of a mess.

I gather there's a relay circuit that helps determines fan voltage, but until the manual arrives I don't know enough about what I'm looking at to do real troubleshooting. I don't want to dig a still-deeper hole.

Originally Posted by uhtrinity

I only see this on the rare occasion I forget to unplug the car when rolling up the windows and it usually clears itself. Worst case, I clear the code using my OBDII reader.

I tried many times, clearing it with my ScanGaugeII each time, but upon startup there's a slight humm from the back for about a second (not the fan, now disconnected, probably the fuel pump), the CEL appears and then the backup 12V starter kicks in. There are no SOC bars from no IMA, but at least the IMA light doesn't light up, and there are no other codes. In driving a few miles yesterday it did not go away.

I just tried again a few times in cooler conditions this morning, no change. It takes about a second for the CEL to reappear upon clearing the code, engine running or not.

Thanks for the response,
Roger
'86 Civic Si active,
2000 Insight 5spd archived until I get things unscrambled

[Mike Dabrowski 2000]

Roger,
The battery fan is controlled by the BCM via two relays, which isolate the fan power from the BCM, so I doubt that you have damaged the BCM.
Since the high speed fan relay connects the system 12V directly to the fan, via the under dash 7.5A fuse #24, start by checking that fuse. The power to operate the relays also comes from that fuse.
The low speed fan relay puts a power resistor in series with the power. The resistor is on the battery contactor assembly, right under the connectors near the front of the IMA box.
The two relays are also on that assembly .
Exactly where did you tie in the reversed 6 V?
The fan it self is much more likely the issue than the BCM.

If you disconnect the fan connector and while again observing polarity, connect just the fan to your 6V or the car 12V, does the fan work normally?

[crx_rogus]

Originally Posted by Mike Dabrowski 2000

Roger,
The battery fan is controlled by the BCM via two relays, which isolate the fan power from the BCM, so I doubt that you have damaged the BCM.
Since the high speed fan relay connects the system 12V directly to the fan, via the under dash 7.5A fuse #24, start by checking that fuse. The power to operate the relays also comes from that fuse.

Of course, the IMA fuse (should have thought of that). Yup, it was blown. With it replaced the IMA works fine again... except for fan voltage...

Originally Posted by Mike Dabrowski 2000

The low speed fan relay puts a power resistor in series with the power. The resistor is on the battery contactor assembly, right under the connectors near the front of the IMA box.
The two relays are also on that assembly .
Exactly where did you tie in the reversed 6 V?
The fan it self is much more likely the issue than the BCM.

If you disconnect the fan connector and while again observing polarity, connect just the fan to your 6V or the car 12V, does the fan work normally?

Here's the latest data:
-1.4V on startup and initial running
0V for much of the drive, perhaps reasonable since I didn't use all that much assist or regen.
-1.4V at and slightly after descending a decent-length hill at full (brake light just barely on to minimize friction) regen about half the time, 84.4 deg. F temperature at fan (sensor between fan shroud and fan casing), 81- 83 deg. interior temp., about 90 degrees at the exit end of the MDM/DC-DC heat sink (temps from indoor/outdoor remote thermometer units).

I had tapped the +4.6V from the charger assembly (6V - 1.4V from two blocking diodes) directly to the fan lead, with the fan running ok from that.

I also found the fan to work fine fed from the 12V outlet with 20 ohms of extra resistance in series with it, which should give it +6V given its 0.6A rating. It was a bit faster than when fed from the charger's +4.4V (2A available) feed, so I don't think the fan is damaged, not the cause of under-volt condition (and obviously not of the reversed polarity). The grid charger was totally disconnected for the test drive where the above data was from, with the fan connected factory-spec to the relay circuit (and only the relay circuit).

Thanks for the replies,
Roger
2000 Insight generally driven in a way that should avoid overheating the uncooled battery pack