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Ask Juan Crespo Your Own Question
Juan Crespo
Juan Crespo, Tech Trainer
Category: Toyota
Satisfied Customers: 1516
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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No communication with OBD 2.... I checked and there is no

Customer Question

No communication with OBD 2.... I checked and there is no signal coming in
JA: Sometimes things that you think will be really complicated end up being easy to fix with Toyota. The Toyota Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: 1999 camry will not communicate with OBD 2 I checked the pin 7 K line and there is no out put... Looking for the logical next step to troubleshoot
JA: Are you hoping to fix this yourself?
Customer: Yes!
JA: Great! What have you tried so far?
Customer: Diagnosing the ports with a multimeter to see exactly what the issue is I did not start taking apart harnesses
JA: Is there anything else the Toyota Mechanic should be aware of about your Toyota?
Customer: nope
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Toyota Mechanic about your situation and then connect you two.
Submitted: 6 months ago.
Category: Toyota
Expert:  Juan Crespo replied 6 months ago.

Hi there.

I might be able to help you, but first I need to ask you a few questions:

  • what's the engine size on that '99 Camry?
  • what is it that you're trying to fix other than no-communication with the onboard computer?
  • are you using a Techstream or equivalent scan tool?
  • is there battery voltage at data link connector (DLC) pin 16?
  • is there ground at DLC pins 4 and 5?
Customer: replied 6 months ago.
It is Toyota 4 cyl. The car runs amazing (for 203k) no problems, except check engine light is on, and I need an inspection. The scan tool is functional, and scans my 2002 odyssey. When I connect to the camry it turns on but gives a no communication error. I then probed the DLC pins 12.4 V on Pin 16. and .28 V on pin 7, 0,0 on 4 & 5 . With battery disconnected I got continuity to 4 & 5 and 800 kOhm to pin 7. I checked the white wire coming out of the ECM under the glove compartment and got t he same thing The way I see it the ECM is bad there is a bad wiring harness or both. I am not ideologically against bringing it in for service. except in this case I am afraid of a fishing trip, trial and error. I would like the best next step for troubleshooting solving,What should be my next step?
Expert:  Juan Crespo replied 6 months ago.

OK. I can see why you would think the ECM is bad - I tend to agree with you there. The only thing that concerns me is that the engine runs good and the CEL is on.

Why don't we test our theory regarding the ECM being the cause of this issue? Do you have access to a known good used one you could swap?

Customer: replied 6 months ago.
I do not... This is where I am stuck.... I see them from the junk yard on Ebay for as little as $20... I dont mind the $ I just dont know if I could be doing more damage. Can You recommend an alternative?
Customer: replied 6 months ago.
OK My ECM is 89661 -06690 .... If I purchase a used one... do all numbers have to match or just the 89661
Expert:  Juan Crespo replied 6 months ago.

To put your mind at ease on the respect, there is no way you can do more damage by replacing the existing ECM with a known good one.

The only thing I would do before replacing the ECM is check the wiring to make sure the serial BUS line (DLC pin 7 White wire to ECM connector E7 pin 16) is not open and the CEL circuit (Green/Red wire) is not shorted to ground between the cluster and the ECM connector E7 pin 4 - you can check this by simply disconnecting the ECM; you'll know there is no short to ground if the CEL goes off. If those are OK, then I would try another ECM.

Compatible Part Numbers are: 89661-06690, 89661-06691, 89661-0669184, 89661-3T270, 89661-3T271, 89661-3T272, 89661-3T27284, 89661-3T450,89661-3T451, 89661-3T452, 89661-3T45284

Customer: replied 6 months ago.
Thank you! I ordered an ECM and will let you know how this works out.
Expert:  Juan Crespo replied 6 months ago.

OK.

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