Home>Automotive>Notes for Brad (v8jagnut) in troubleshooting his SV21 Camry issues

Notes for Brad (v8jagnut) in troubleshooting his SV21 Camry issues

These are for for brad aka “v8jagnut” on you tube. For those who are unaware he is having issues with this car:


Its sad that the shop he took the ECU to diagnosed it as bad. I took a good look at the code charts and diagrams after watching your video, I guess it is possible that it could still be something in the wiring regarding the voltage reference supplied by the ECU. I am not sure if you have the diagrams or just googled around for it but I have found and posted the following findings for you: (all images are clickable for high resolution ones, sometimes you have to click twice)


In considering the codes in your video above there is a single circuit that ties all of those sensors together, the reference voltage output. For those who arent familliar with EFI this is how this portion works; The ECU supplies a clean regulated +5volt signal to some sensors on the engine, the coolant temp sensor, MAF, and TPS. The reason why they cannot supplied 12 volt power is because the 12volts while it is regulated to an extent via the alternator the electrical system overall still varies a considerable range. So if you’re taking a varying voltage and putting it into the sensor, you’re going to get varying results or readings back from the sensor.

So using a 5V regulator, this can guarantee that the sensors will have a solid 5Volts to work from, and the ECU is happy because it knows where things are at.

I have highlighted the affected wire below in RED:

Either the regulator is hosed in the ECU, or there is wiring botched somewhere in the mix, and its taken out the 5volt regulator in the ECU.

I think as a good test before trying a known good computer you should unplug all affected sensors on the circuit, unplug all connectors from the ECU and check continuity between the reference wire and ground, there should be none. (open circuit)

If anyone is attempting ecu board repair some good tips and tricks can be found on my ECU Chip tune page:

*remember all repairs are at your own risk, I will not be held liable for any mis use of this information*




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