Fried ECM Circuit

I took my 96 3.4 Tacoma to the shop for help troubleshooting since my cheapo scan tool wasn’t connecting to the ECU. But now it turns out a circuit on the ECU is fried. They quoted $1000 for a used one that may or may not fix the issue. A couple weeks ago it was working.

Is this a common issue? I’m wondering what my best options are.. apparently it also has a knock sensor code (according to PO), and feels like it’s in limp mode. Could that be caused by a bad ECM though? And what’s the primary cause of a fried circuit?

i thought it was very rare for these electronics to go wrong so I’m wondering if someone has been messing with the wiring.

Any insights or advice would be appreciated. Thanks.

 

I would want to know which circuit was fried and how they came to that conclusion.

 

Thats a good point. I didn’t get that into the weeds with it but I can ask tomorrow. I don’t have much knowledge of electrical troubleshooting.

 

Does the check engine bulb light when you have the key in the on (engine off) position?

 

Search results for: '1997 toyota land cruiser' (fs1inc.com)

 

Yes it’s always on actually. The PO told me it was a P0324 code but I’ve been unable to confirm.

 

This is for a 1996 Tacoma with the 3.4 V6 but thanks for the link

 

That's just a knock sensor code. What is your original issue with the truck?

 

Search results for: '1996 Tacoma' (fs1inc.com)

Search is your friend.

 

Yea I found it thanks

 

Well I’ve been having idling issues on startup (low and rough when cold) and the truck feels underpowered like the timing is being retarded. I was unable to pull codes to confirm what the PO told me which led me to the ECM issue.

 

I would go to Walmart or somewhere else where you're able to take it back if it doesn't work for you but try a different scan tool. If the mechanic got theirs to connect then at least the computer is communicating. You can get a cheap autel for 40 bucks at Walmart with live data. Posting screens from the scanner during idle to this forum should help in order to discover any irregularities if you're not familiar with the PID information.
I would definitely be asking more questions and poking around a bit with a scan tool before even considering dumping money into an ecm.

 

But the short answer to your question is yes, the ECM can cause those problems but so can just about anything else.

 

I’ve tried one at Autozone also and it wouldn’t connect. I know at least the port of getting power though but it just doesn’t wanna connect. The parts guy tried to tell me 1996 was too old to work with them but OBD2 is OBD2.

 

There are a few protocols on the OBII connector, I actually have a hand held scanner that works with my 98 taco but won't work with newer cars. I would check the website of the scanner manufacturer to make sure it supports 96 taco or use those newer phone based scanners - those always seem to work. From a google search-


There are 5 different protocols defined on the OBD-II connector, including J1850 PWM used by Ford, J1850 VPW used by General Motors, ISO 9141-2 for Chryler, ISO14230 KWP2000 on some EU and Asian cars, and most important from our point of view, ISO 15765, which is CAN for vehicles. Since 2008 all new vehicles have had to support CAN, so the other protocols will die out over time.

 

I don’t think it’s the reader: it worked on my 97 and worked briefly with this truck one time.

Now they’re saying no ECMs are available anywhere in the country for my VIN. Only 2 used options available countrywide.

 

If the engine starts I doubt the ECM is beyond being rebuilt I have had a few rebuilt . Check out ECM Depot

Then it also might be as simple as a broken wire.

Last used ECM I bought was $100.00 for a 98 4Runner.

2 Things that ECM don`t enjoy water and voltage spikes if someone applied system voltage to the wrong circuit .

 

Apparently one of the circuits is visibly fried.

 

I wonder if someone was tinkering with it. It does have some aftermarket add ons