obdii scanner fails to read data
 

So what could cause an over the counter obdii scanner to not be able to read data from my '97 c4s?

I had to replace a dead battery over the weekend and now I'm trying to confirm readiness codes are reset in anticipation of a second attempt at a way overdue smog test.

I bought an AutoXRay codescout 1500---because that's what was in stock at the local NAPA I passed on the way home from failing said EPA test---but it will not read any data. It shows that it connects to the car and then attempts to read codes but after about 30 seconds or so returns a code of "read attempt failed. make sure key is on and both ends of cable are firmly connected".

I reset the memory on the scanner a few times, and I tried connecting the scanner to the obdii port both before and after switching the car on, etc. but no love. The guy behind the counter tried it on two cars in their garage (97 cherokee and a 98 isuzu) and it worked fine on both (I saw the stored codes). So NAPA wouldn't refund my money because in their opinion it worked on another car, i.e., must be a problem with my car, despite my EPA test dated today in which their scanner was able to read the codes without issue.

AutoXRay tech support says they will not honor a return either and contend the problem is with my car: "my car must not be odbii compliant and the reason the test machine at the epa station works is because it attempts to read data off all the available pins and theirs only looks for data on the two specifically named in the RFC for odbii data transfer." I'm fairly certain I was able to pull codes before from a different type of generic code reader and I know I've seen posts here where odbii 993 users specifically referenced this particular scanner worked on their car, so I'm a bit baffled, and a lot frustrated.

Any recommendations or suggestions from anyone else who may have experienced a similar problem when trying to read codes via a generic odbii scanner would be greatly appreciated.

Many thanks in advance,
Jason

You need to make sure the ignition key is in and the immobilizer is "off" like you are going to start the car and you are to the dash lites position on the key, then it should read fine

Chris gives great advice.
Not having the immobilizer defeated kicked my a$$ for an hour or so as i was trying to read codes.

cheers

Craig

+3 on immobilizer.

It needs to be turned off before data can be read. It literally disables the ECU along with the ODBII port.

Trailblazers..... I am doing this Friday! Thanks!

Thanks for the feedback gents. Is there more to defeating the immobilizer than pressing the button on the remote, because I've been doing that prior to attempting to read the codes up to this point?

To be more specific, I've tried to read the data in the following ways, which all ended in the same error code: unable to read data; ensure the cable is connected and the key is in the on position:

1) from unlocked car, open door, connect cable (lcd on the scanner changes from "disconnected" to "connected"), turn key to on position so all lights on dash are on, press read on scanner > error code returned after ~ 15 seconds
2) same as # 1 but switched car on before connecting scanner to obdii port in car
3) same as #1 but actually cranked car (rather than just turning key to on position)
3) same as # 3, but cranked car before connecting scanner to obdii port in car
4, 5, 6, 7, 8) tried all of the above from car being locked and using remote to unlock car before beginning

since your replies last evening, I did repeat each of these scenarios to confirm the immobilizer light in the clock was not lit prior to proceeding. Is there an additonal step I'm missing as regards the immobilizer? (Sorry, I would rtfm but it's not at the same address currently)

Thank you again for replying; it is most appreciated.

Jason

Sounds like you are doing everything correctly to me. Are there setup requirements of the reader you haven't done? I use Auto Enginuity's program through my lap top and I have to tell it what year and car etc...before it will read. I don't have any experience with the hand readers like you have, and I'm not aware of any fuses that would stop you from reading through the OBD connector.

Thanks Chris.
It was plug and play on the other two cars I witnessed it work on. There is no set up options or parameters to set before connecting, just read, clear and enter buttons, pretty foolproof (but apparently not enough, as I'm still at a loss).
I use ECU explorer on my other car, which is a full-blown, laptop based software package for real-time data logging so I thought this would be a piece of cake in comparison (drivers, install codes changing with every laptop change, etc.).
I know a few other people on the 993 board are using this brand so hopefully they know some trick to get this to work.
But, looks like for now my attempt at confirming readiness code reset myself to save some money went out the window, as now I have to not only pay my mechanic to do that, but also to explain to me why I can't figure out how to operate my newly bought dyi tool...oh the irony...

Something is up with that scanner then. Get an Actron.

So Ironic, I just tried to get my car emissions tested and they said that they could not read any of the codes. They told me to drive it 10 days then bring it back.

they said they were scrammbled like the data had been erased. I know they had the car on too, possible DME issues?

Well if that doesn't suck :banghead: why don't you bring it to a local auto parts store? Down here, the local Autozone/Advanced auto (what ever you may have...Kragen, any of those types other than a PepBoys) reads them for free and will even give you a print out.

Cohare, now, that sounds more like the results you might get if the immoblizer has not been defeated prior to scanning, but I can't confirm. When you say "on" do you mean the car was cranked and running? If so, then that trumps my situation, and I wish you the best for the re-test. In my case, the EPA test station equipment read my codes without issue (unfortunately they all returned values of "not ready").

A good track w/e will fix that :D usually does mine! I come back and all reset, must have something to do with all that full throttle running :)

will give that a try; at least then i would know if it's my car or this particular brand/model of reader.

that would be the preferred method, but I have to get my plates legal to get be able to drive to a track first!!

Thanks again for all your feedback Chris. I'm a displaced NC native and I sure do miss it sometimes.

Cheers,
Jason

Well feel free to give a holler if you get down to the beach :thumbup: