SOLVED! PCM firmware re-flash solved the no-start condition! SOLVED!


2006 FEH no start. I have searched and read through dozens of posts and have done the following.

New fuel pump; new fuel filter; new 12v battery; checked grounds; checked inertia switches (ok); removed, cleaned, replaced all fuses, solenoids and harness plugs; Cleaned all with DeoxIT; New 100A main fuse; Checked mecs pump (ok);

Also, I forgot to mention the two persistent failure codes .... P0A95 (High Voltage Fuse) and P1A10 (battery disable by HPCM)

After leaving ign on with accessories plugged into 12v and 110v outlets, 12v was dead and HV was at 4% SOC. Car ran fine before this.

Trickle charged HV batt to 85% SOC.

If I turn ign key from off to crank, the ICE engine WILL crank and start for a few seconds before the BCM signals to shut down the HV battery.

I have a current theory now that I’ve gone through everything else. But I don’t want to bias the pros (you all).

Some curiosities. Why did the battery management ever let the HV get to 4%? I thought it shut everything down when 12v or HV got low.


https://www.greenhybrid.com/g/album/19664290



Here you can see what happens when ign key from off to crank. initially all is ok, then HV gets shut down.

 

You've done an extensive amount of work, yet you've failed to indicate why. What's the history of this vehicle that required so much work?

How long did you charge it? Why didn't you use the built-in jump starter?

 

I used the built in charger many many times. it just didn't seem to be moving the battery SOC up from 4%. Also, about every third time I tried using it, the green LED would blink and a battery jump fault would show up in ForScan. I put the 300mA charger on the entire HV battery, on and off, for about 36 hours. I had to monitor temps closely, as they would go towards 110F. Of course I had to keep the new 12v adequately charged to run the HV battery fans, etc. I never saw the HV battery voltage go below 345v or so, when depleted.

All trouble began after I accidentally left ign on for a full day. I have been checking things and doing work based on advice and from most to least likely, and cost effectively. Things such as fuel pump and filter and 12v battery I wanted to change anyway as a matter of long term maintenance.

It's clear from watching ForScan that one of the control modules, likely the BCU (?), is requesting shut down based on a parameter, or something, coming from the HV.

 

Gotcha. For future reference, it's rarely necessary to charge for more than 4 hours. 4 * 300mA = 1.2Ah = 1.2/5.5 = 22% SoC minimum.

1. Did you note that the HV battery was at extremely low voltage before the first attempt to jump start?
2. What is the resistance between the posts on the safety plug?
3. Did you loosen the two small 8mm head bolts between the relay and the main terminals?

 

Thanks, in future will not charge beyond 22% SoC.

Yes, the HV battery was never low voltage before the first jump starts with little button in footwell. It was always around 340v.

I'll check resistance, but I got a known good, and that didn't solve problem.
Yes, I did loosen those, in fact I took all that apart to attache 300mA charger. Why, is that a critical point?

Also, I forgot to mention the two persistent failure codes .... P0A95 (High Voltage Fuse) and P1A10 (battery disable by HPCM)

 

Did you torque the two bolts to approximately 50 in-lb?

 

"Did you torque the two bolts to approximately 50 in-lb? "



No, I did not do that. I can, but will need to source a wrench. I'm stranded in San Diego 200 miles from my tools.

I can't understand why the BCM would let the HV battery get so depleted! Also, does the variation between MAX and MIN SoC look ok to. you? I think it's 13%

My theory is that the BCM or another control module is bad. But I'm unsure, of course. I'm in San Diego starting to look for a used HV batt.

 

I don't know the specifics of the FEH management, but a Toyota will let it go to 0% SoC before it pops the relays and disconnects the battery. Either way, 4% or 0% isn't really accurate. There's still likely more than 10-20% remaining.

Failure to adequately tighten those causes a huge voltage drop.

Possibly BCM or PCM or try this:


If they reach, you can short them together and skip the jumper wire.

 

Must figure out how to scale down images. Bolts torqued. Batt + and - connected for 20 min. Ω of 100A main fuse reads .1, I think. See image of meter.

going to put it all together and try, will report back here.

 

Yep. 0.1Ω

Were the bolts loose?