RED TRIANGLE Gen 2 2005-2009 Prius Transmission Failure, Inverter Problems

Gen 2 Prius (2004-2009) RED TRIANGLE Transmission Failure, Inverter Problems

Red Triangle Warning – Long ago we published an article on the Gen 1-3 transmission failure .  Around the same time we predicted Gen 1-3 transmissions would be more robust.  While this remains statistically true, our experience has proven that they are not immune to transmission problems of their own.  And many times they come on due to extended period s of driving with the red “Triangle of Death”.

Common symptoms of this problem include:

Whining/growling noise when engine starts
Rattling/banging when driving
Car refuses to “ready”
Engine cannot start (“whizz” noise when cranking)
Master warning light (red triangle)
Diagnostic trouble codes will include the following error codes….

P0AA6, info codes 526, 613: High Voltage Isolation Fault
P0A7A: Generator Inverter Fail (over current by inverter assembly malfunction)
P0A92: MG1 malfunction

Many companies currently operate an overnight shift 7 days a week dedicated to hybrid cars that serve as taxi cabs.  With this experience we can describe Gen 2 Prius transmission failure as routine, somewhere between 150-250k miles just from their research alone.  The most common indication is trouble code P0AA6 (with no other known symptoms), but we have also seen broken chains, failed bearings, bad MG1s (trouble code P0A7A and P0A92), and seized planetaries altogether. 

We have also seen these problems on many other privately owned cars, as they get much older.  Not only have we seen failures in transmissions and inverters due to driving with the red triangle warning in the process we’ve developed industry-leading procedures for testing insulation, impedance, and mechanical problems to prove this issue.  We are leaps and bounds ahead of the dealer.

Right now we can repair the car at a fraction of dealer cost with second hand units and honest labor charges. Over the years we have replaced dozens of Gen 2 Prius batteries and inverters due to running the car while the red triangle warning is still showing issues.

Transmission Noise You May Hear:

There is a flat needle bearing that holds the planetary gearset from the MG1 case.  This bearing is the weakest mechanical link, prone to failure over time.  Once it collapses, the gear it supports falls inward against the load of the chain and grinds into the case of MG1.  Early signs are a whine when the engine starts .  Long term the chain will break and when MG1 attempts to crank the engine the planetary freewheels with a “whizzing” sound. You will know what we mean when you hear it.

Winding deterioration is also possible in MG1, the smaller motor/generator inside the Toyota HSD transmission. Symptoms may be similar to the noises of a bad bearing or broken chain, because MG1 is engaged when the car attempts to crank the engine. Sometimes the gearset makes noise, but sometimes the motor is bad enough that the inverter will simply default when attempting to engage it, much like a bad starter making a single “click” noise when trying to turn over an older model car . When attempting to “ready”, the click is heard and then the warning lights appear, and the car is incapable of starting the engine. The vehicle will still move under the power of MG2 (the traction motor) but the HV battery will eventually deplete to the point that it will ready off and it will no longer attempt to restart at all. At this point the damage is done.

Both of the trouble codes relate to the inverter, which is why it is so often condemned as the source of the real problem. The inverter provides power to the motors, and when a short in the inverter current peaks, it in turn, sets off  a warning code. This is exactly the same scenario as P3125, info code 287 with Gen 1 Prius. Sadly,  We expect many inverters will be thrown at Gen 2 Prius, despite the experience with earlier models.

Cost of the problem?

Well, this can cost you upwards of $2500.00 to $3500.00 for a transmission problem but we can still save you thousands by eliminating the problem altogether.  When you see the warning light give us a quick call and we will give you and honest answer on how to keep your hybrid running for years without draining your entire savings.

Give us a call at 727-565-5685. Ask for Paul.  I will give you an honest up front answer.  We have been know to save many Tampa Bay customers thousands of dollars. Just ask our previous customers.