So I went to get a SMOG check on my 2000 4Runner thinking that I will be in and out in 15 to 20 minutes tops. Anyway, 5 minutes into the test, the guy comes back and tells me that my OBD has no power, meaning that it is not talking to the computer. Has this ever happened to any of you guys??? Just to make sure, I went to another SMOG shop and had them just check to see if it's my rig or their equipment. The guys comes out with what I am guessing is some sort of a scan tool and hooks it in near the accelerator and NOTHING. It is very frustrating because I passed Comprehensive Visual Inspection and Emissions Test. The one I FAILED was the Functional Check. The report says "The vehicle failed the MIL/Check Engine Light Test due to OBD Communication Failure." Any thoughts????

I checked the fuses right below the steering wheel to the left and it looks like the fuses are in good shape. So what could it possibly be??? Thanks in advance for the help.

 

start with checking fuses

 

So far, I have checked all the fuses under the steering wheel and none of them seem to be blown. Also, I did have my Air/Fuel Sensor (O2 sensor) replaced a month ago and the Check Engine Light was cleared after that. Also, my alternator was replaced by a reputable shop.

 

be honest... did you try clearing the light before you went for the test? if so. there is your fail... or whoever did the o2 sensor and cleared the code must have tamered with soemthing. or try wiggleing all the wires behind the plug. or get your reading glasses on and check out the fsm over at www.ncttora.com

 

Exactly the same thing happened to me yesterday, with my 2004 Hyundai Elantra.

I went to a Test Only Station and passed the Visual and Emissions test, but failed the Functional check due to "OBD communication failure". I paid for the test and went to the dealer.

At the dealer the Service Writer told me that certain stations have out of date software, and may have problems with certain specific makes and models. He sent the car to the place the dealer uses and the car passed the test with flying colors.

So it was not the car's problem but the station's problem. I'm going to report this to the state and try to get my money back from the first station.

I hope this helps!

 

By the way, I also learned that you can ask the Test Station to try to communicate with the DMV before actually performing the test.

That way you won't pay for the Test unless it is confirmed that your communication system will work.

Of course, if you do not say nothing, they will try (as the first station I went) to run the whole thing and charge you, even though they may know that the car is not talking to the computer.

It sucks, but you know how people is when it comes down to money.

 

I went through all the fuses and realized that it was the OBD fuse in the engine compartment. So I replaced it with another 7.5 amp fuse and it has work so far without any Check Engine Light coming on.

So I know everything is good to go, but does anyone know if the vehicle will require some sort of a drive cycle waiting period. I ask because I popped in the replacement amp so does the ECM/ECU start reading the OBD since then???

This is why I am giving it one more week of driving before I bring it back to the place for a free one time retest. Crossing my fingers that it will pass.

 

if i recal correctly that fuse is only for the obd2 port. So maybe the shop that did the work... tried to clear the code with a faulty scanner that fried the fuse.. it happens..