ECU bad?

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ECU bad?

Postby mpg » Thu Dec 08, 2016 6:14 pm

Greetings,

I recently had the car serviced and was told that it was not table to have code 21 cleared from the CEL due to the oxygen sensor heating circuit being bad (which is in the ECU?). The car had a new Oxygen sensor put in and the problem persists. The wiring was traced back to the ECU with no breaks. As a result, they took out the CEL (which I'm putting back in) Is the ECU bad or is there a way to fix this problem without replacing it? This post is related to a previous about the cat not making full boost, now i know why (Thanks!) 1988 ST-165.
If the ECU is bad and needs replacement, where can I find one?
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mpg
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Re: ECU bad?

Postby Toxygene » Fri Dec 09, 2016 4:15 pm

You can sometimes find JDM ecus on EBAY and on The Japanese Yahoo pages.

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Re: ECU bad?

Postby Ryan » Fri Dec 09, 2016 7:19 pm

I have a usdm ecu as a spare... Pm me

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Re: ECU bad?

Postby 88gt4DE » Sun Dec 11, 2016 2:47 pm

Brother had same issue ... It is possible. You can open ecu and look for fried resistors. I would source another before trying to do any surgery to repair it or you may be able to find someone that still repairs them professionally.
Rob
1988 ST165 - 77K - Project ---> http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=31483&start=240
2000 Toyota Tundra SR5 - 162K - DD - Thanks 97JZA80
2007 Toyota Rav4 - 110K - My girls DD
1999 Honda Civic - 116K - Highway Runner
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Re: ECU bad?

Postby mpg » Mon Dec 12, 2016 9:22 pm

Thanks for the replies and help.

I got the dashboard apart last weekend and replaced the CEL light and ran the diagnostic, turns out I have codes 21 O2 sensor and 52 Knock sensor showing.
The O2 sensor was replaced during service ( not sure if it's the right one and I didn't change it) and the knock sensor was not. Don't have the old ones.
I followed the troubleshoot sequence from the big green service manual for the O2 sensor( the one for the Celica 1988 with 3S-GE) that showed during high idle, the voltmeter at T-E1 terminals fluctuated between 9.9-10.1 Volts and less than the 8 times in the 10 second range for spec. It says to replace the sensor, there is no procedure for that in the the smaller green service manual specific for the All Trac, it says to use this procedure from manual RM-071-U the big green book I that I used.
Going way back to 1997 when I bought the car, remember replacing the knock sensor, it has probably 85K miles on it since. There is no test for the knock sensor at the ECU or manual that I could find.
At this point I'm looking to replace both as i can get them and don't want to open the ECU probably alotl less $$ than trying source a replacement.
Again your help is appreciated, thanks.
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Re: ECU bad?

Postby mpg » Sat Dec 31, 2016 3:21 am

Ryan wrote:I have a usdm ecu as a spare... Pm me

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Ok, whats your price for the ECU - 1988, Yes?
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