HiHy Gen 1 (Highlander Hybrid 2006-2007) troubleshooting

My HiHy has excessive idling of the ICE.

When I am parked with the car in READY (I end up having to do this a lot for work, etc), the hybrid battery will continue to drain (normal). When the battery gets particularly low, the ICE will come on and the MFD will show the battery being recharged (normal).

The first thing I will say that I notice is that the ICE seems to run for a good while (more than a minute, maybe as long as 5) before I see any more bars added back on the MFD (IDK if this is normal or not). Eventually, the bars will be almost full, and the MFD will show the battery no longer being charged (normal).

However, despite the battery no longer being charged, the ICE will continue to run (NOT normal I assume), even to the point when the battery is run down again and starts charging again!

If, however, after the battery finishes charging, if I shut off the ignition, then "crank" the car again, the ICE will come on momentarily (normal) before shutting off (normal), and remain shut off until the battery is drained (normal), at which time it will come on (normal) and begin charging the battery (normal), and although it will take a few minutes for any bars to be added back to the battery (I don't know whether this is normal), the battery will return to a high state of charge (normal), and the battery will stop charging again (normal), however the ICE will continue to run (NOT normal), unless I turn the car off and back on again (which I never had to do with my Prius).

I hope I explained that clearly enough

 

Thanks for the reply. She's at 220K, and I don't show any records on Carfax or Toyota.com that the HV battery has been replaced.

Still, She will fully recharge, I just don't understand why the ICE refuses to shut off.

I just got an OBDII Blutetooth connector. Can I use that to test the HV battery health?

 

Still no CEL.

Running Dr. Prius, the modules are reporting ~0.2v difference.

I made enough racket that the shop foreman at my dealership had me bring it in so he could plug in a Techstream. He also was seeing voltage differences that were within spec. He thought the battery appeared remarkably healthy for 220K miles and 14 years.

The other thing we checked was SOC at beginning and end of the cycles. It is consistently around 38.5% when it starts charging again, and 58.5% when it stops charging, only there are still times when it stops charging, but continues to run the ICE!

The shop foreman was utterly convinced that without a trouble code, there's nothing to fix. While I understand where he's coming from, I see no reason for my gas to be burning when the engine is not providing me with power, electricity, or heat. He was convinced that it must be doing "something," because while he understood why I wouldn't think it should run, it "must" have been engineered to work that way.

I remain unconvinced, but also unaware of what I might do next

 

Sometimes it will do that and only add a bar or two of charge before shutting off. Usually, it will go from 2 of 8 bars (38.5%) until 6 of 8 bars (58.5%). Only 20% by SOC raw numbers, but 50% by "# of bars"

Other than EGR standing for "exhaust gas recirculating," I'm not sure about your first question.

IIRC, there was a capacitor that had to be replaced in all the Gen1 HiHy's. The firmware recall had something to do with air/fuel mixture, IIRC

 

The battery was previously tested at Autozone, but I took it to Advance yesterday to make sure. They say it is good, and it is < 12 months old, IIRC.

The car is new to me, and my first HiHy so I'm uncertain as to "normal" behavior. I will say that it burned 4 gallons of gas overnight, whereas my Prius would only burn a gallon or so