Electric rear engine not working during strong acceleration.

[Tydirium]

Hi, I've got a 2007 RX400H , the rear electric engine not working during strong acceleration but it work well in full electric ? An idea ? Thx

[RX400h]

Hello, Hugo. Have you checked for codes? How many miles are on your RX?

We have almost 140,000 miles on ours and have never experienced what you describe.

[Tydirium]

Hi Dave, no I haven't check for codes I must buy a license for my diagnostic tool so I ask first, my RX have 112000 miles, the only thing happen since my issue is a discharge of the 12v battery.

[Mbosque]

Hi Hugo, as Dave suggested first check for codes. 

As you’ve indicated, the 4WD RX 400h typically engages the rear traction motor only in certain high load demands and stability situations. Otherwise it will assist with power regeneration when appropriate. 

If its drive engagement has changed from your typical driving experience and there are no obvious codes, it may require further diagnosis on a dedicated 4 wheel driven chassis Dynamometer, with the RX in 4WD inspection mode. I’d try having this done at a shop with the Toyota Techstream software, to be able to catch any anomalies while running. 

If it is intermittent in nature from normal, I’d look for corrosion on connectors and wiring harnesses from the rear motor to the Hybrid ECU. But also check the rear transaxle fluid level and its condition. It takes 1.9 qts ATF WS (toyota). Perhaps there is some safety kicking in if there is an issue with the rear transaxle and heat in high demand situations.