PCM Failure?

[Paddo]

I'm wondering if anyone has had their Powertrain Controle Module fail in a 3rd gen 4Runner. Mine is a 2000 Limited.

I've had codes P0135 and P0141 for a while, and finally got it into a shop today. The techs tested all the circuits on both O2 sensors (49-state), replaced the O2 sensors, and consistently got an open circuit on the heater circuit, which should have a pulse-width-modulated signal. Three different techs tested each circuit and they all said each circuit was good. They determined the cause was a failed PCM, which was exactly what I was hoping it wouldn't be. They all said they'd never heard of that happening on a Toyota before. I've done some reading in the past and thought that might be a possibility, though.

So my question is: how often does this happen? And how much would I be looking at for the price of a new computer?

The guys at the shop are going to look around for used ones for me, to avoid buying a brand new one. Does anyone have experience with this?

Thanks

 

[EatonKyleH]

Unlikely...But Possible.... however impossible to tell you over the internet without actually testing it.

But it wouldn't be the first time I've seen these 2 codes (and only these two codes for some reason) be caused by a bad ECM/PCM ground.

Here is how you'd test for a weak ground that would absolutely result in the setting of the P0135 and P0141 combined.

1. Attach a volt meter to the White wire at the bank one sensor one harness connector. With the key on battery voltage should be present. Start the engine and the voltage should drop close to 0 volts and remain at 0 volts for up to 20 seconds.

2. If the voltage on the White wire does not go close to 0 volts, check the ground on the intake manifold for being loose. The ground on the driver's side of the intake manifold can cause the heater codes

you could simply try cleaning and reattaching the ground but without the above testing you would not be testing the wiring and grounds effectiveness

 

[Paddo]

Checking the grounds was one of the first things I did when I started getting the codes. These guys had my 4Runner all day, tested it over and over, with several different O2 sensors, and they tested every circuit already. Three different techs tested it, and said all of the circuits were good.

I believe they said they were getting .01 volts on the ground.

 

[xcmountain80]

New PCM will run you $150 or so on ebay.

 

[Paddo]

Great, I was hoping it wouldn't be crazy. Any idea on the install time? That's something I've never messed with before.

 

[Kenworth]

Install time at most 1/2 hour, I have ECM out of a 98 3.4 if that would work not sure 75.00 plus ship