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Chris (aka-Moose)
Chris (aka-Moose), Auto Technician
Category: Toyota
Satisfied Customers: 47661
Experience:  16 years of experience
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I have a 2006 Scion TC that I just swapped out the engine

Customer Question

I have a 2006 Scion TC that I just swapped out the engine on. The dashboard just flashes, domelights, nothing works at all in the car If I hook up my OBD II to the car, it works fine Disconnect and everything electronic is un-responsive Hook it up, and it works again
JA: Thanks. Can you give me any more details about your issue?
Customer: Well, with the motor swap, we used most of the original sensors off the car except for the Temperature sending units. It's all installed except for the radiator and sensors to that and the intake MAP Sensor is not connected either
JA: OK got it. Last thing — Toyota Mechanics generally expect a deposit of about $20 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Toyota
Customer: replied 1 year ago.
OK I made the payment of $20. So what's going on" Car is 100% dead with zero response to any switch or button - blinking lights on dashboard, blinking dome light - Key does nothing when you try to start it. Hook it up to an OBD II and it works fine. There are no codes other than Mass Flow and Inlet air temperature as I don't have the inlet hooked up yet. Sensor plug is just dangling there
Expert:  Chris (aka-Moose) replied 1 year ago.

Welcome, I'm Chris (aka Moose). Experts aren't employees / agents of Just Answer. We are independent service providers using the Site to sell their Expert knowledge to Customers. I strive to provide EXCELLENT 5 STAR service, let me know what's needed from me so your pleased.

Just to make sure I understand, you connect a scan tool, and the car will crank, start, and run fine?

Customer: replied 1 year ago.
crazy. Without the OBD II connected, it does nothing. Lights wont turn on, key does nothing, no electrical switch at all works, signals are flashing, domelight is flashing. Connect the OBD II and it works fine. Everything works fine
Customer: replied 1 year ago.
The car had been sitting for about 3 months with no battery before I started the replacement so not 100% sure this condition is due to the engine swap but highly likely. That is, I did not test the car before I started the replacement as the prior engine was seized.
Expert:  Chris (aka-Moose) replied 1 year ago.

Most likely there is something on the data communication circuit that is pulling the power from it and this is causing module communication issues, and the scan tool is allowing the circuit to power up. When the scan tool is connected are you getting any U codes? Can you communicate with all modules?

Thanks for asking your question and letting me try to help you.

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Customer: replied 1 year ago.
I am not getting any codes other than MAF indicator and Inlet air temperature (Since these are not connected I would expect them). Other sensors appear to be communicating to the OBD II but it's not finding this massive error. Yes, the OBD II is bypassing something and allowing the system to power up and operate normally but I need to know what to do to fix the system. I know what I am seeing already. I have no idea how to fix it
Expert:  Chris (aka-Moose) replied 1 year ago.

Back probe the data link connector green black and white wires. See what voltage they have with the key on. Then plug in your scan tool, does the voltage on these wires change?

Customer: replied 1 year ago.
Ok will give this a try tomorrow. and let you know
Expert:  Chris (aka-Moose) replied 1 year ago.


Customer: replied 1 year ago.
The systems also all work fine with my son's HUD (Heads up display) connected. That has a secure snap in connection to the OBD II port for the HUD. Think we are putting the ECU at risk if we run the car with the HUD connected to the OBD II port? It ran like this before for a few months when he was using it.
Expert:  Chris (aka-Moose) replied 1 year ago.

I do not believe running with the HUD plugged in is going to hurt a thing.

Expert:  Chris (aka-Moose) replied 1 year ago.

I like to stay in contact with my customers that appear not pleased, still working on the concern, or have not rated yet. I assume you were not pleased with my help. I hate that you have spent money to get an answer but left not happy. Can you tell me why, or can I help more. If its more help you need just reply and we can pick up where we left off. I am also sending an offer allowing me to upload diagrams or repair guides if that helps.

Thanks Chris