Starfighterpilot Posted January 31, 2011 Report Share Posted January 31, 2011 (edited) Let's say that you have a bad CTS or O2 sensor and you check the error codes and you get the code for it. You replace the bad CTS/O2 sensor with a tested good brandy new one. You do not disconnect the battery cables from the battery for 1/2 minute to reset the error codes. Altho FSM 14-50 (3) specifically states to disconnect the battery to erase the code(s) after a repair. SUPPOSE YOU DON'T. Is the ECI ECU still seeing the CTS as bad (cuz it's still got the error code for it)and disregarding the good signal it's receiving now from the good new one for managing the FI system? I may have missed this in the FSM, but I cannot find the answer to this question. Anytime I have replaced anything in the ECI system I have always disconnected the battery to clear the error code(s) - but do I REALLY have to in order for the ECI ECU to operate correctly now that the root cause of the problem is gone and no longer generating a error signal or code? BTW - I always disconnect the battery before I do any electrical work/replacement. I don't like burning up stuff. Thanks In Advance KEN Edited January 31, 2011 by Starfighterpilot Link to comment Share on other sites More sharing options...
Shelby Posted February 1, 2011 Report Share Posted February 1, 2011 the ecu is not that smart,, once it's trip'd into a limp in mode,,you need to reset the ecu,,by removeing batt power ,,now on acasion the ecu may not have to be reset it depends on the exact details and lenght of time the failure last'd example a false reading may have to last for a peroid of time, say 5-10 min,,if the failure was repair'd before that limit was set the ecu may not list it as a hard code and not need tobe reset,, but it's just as easy to reset the ecu and alow it to reprogram it's idle etc Link to comment Share on other sites More sharing options...
Caliber308 Posted February 1, 2011 Report Share Posted February 1, 2011 Whenever I have reset the error codes to the ECU, I disconnect the Negative cable and go have a beer. Appox. 20 minutes later i'll hook it back up. Works for me Bill Link to comment Share on other sites More sharing options...
The Rabbit1 Posted February 1, 2011 Report Share Posted February 1, 2011 The idea is that an ECU can possibly "learn" the values of the new sensor and since it believes the sensor to be bad accept those values to be bad and therefore making the repair worthless in it's eyes. My brother in law just installed a brand new throttle body and tps on his truck and didn't reset the ecu. (His truck has the new "GM drive-by-wire" throttle) Started her up with the codes in memory, the new throttle body does the same thing, so now he just had to reorder a complete throttle body. Did the failure to reset his code cause it? who knows.. Link to comment Share on other sites More sharing options...
Komeuppance Posted February 1, 2011 Report Share Posted February 1, 2011 The SQ error code system is not adaptive. Once it sees a bad value, it'll keep outputing the error to the diagnostics port until it is reset. If you fix the CTS with a good one, and the error code is still there, the ECU will still read it's values and continue to operate normally. This is what I've learned from my experience anyway. -Robert Link to comment Share on other sites More sharing options...
Indiana Posted February 1, 2011 Report Share Posted February 1, 2011 The codes are pretty much useless. Look at the ECI checker chart, get you a $4 volt meter and check at the ECU and look at the voltage that the ECU sees not out at the sensor. If you can't do that you might as well just give up. Those codes are thrown for many reasons none of which have anything to do with the sensor being bad and maybe not even out of adjustment. What matters is that the car runs and it can't run, stock, unless sensor inputs are where they are supposed to be and none of this fixes ignition problems, leaky BOVs or dirty injectors or bad grounds but these can throw those codes all day long.http://www.b2600turbo.com/images/errorcodes1.jpg Link to comment Share on other sites More sharing options...
Raider 2.6 Posted February 1, 2011 Report Share Posted February 1, 2011 When I replaced my o2, the one blink code would go away after just replacing the sensor and not disconnecting the battery. I read in the FSM that the o2 code is always present until it begins responding, however. I do know I disconnected the ISC and it has thrown the 6 blink code ever since and I still have yet to disconnect the battery. The o2 still shows up and goes away along with that code. While we're talking about codes, whats the deal with the other codes? I thought I had read that ETACS and HVAC codes were available somewhere? Link to comment Share on other sites More sharing options...
Shelby Posted February 1, 2011 Report Share Posted February 1, 2011 they are but retreveing them is nothing so easy as ecu codes , this is nothing new, i don't recall any euro cars haveing trouble codes you could retreve , if a part went bad the system ran screw'd up untill you repair'd it if it ran at all , this limp in mode is some thing t he later yrs came along with and as to our quest ecu learning ,the only thing it learns is idle voltage setings , notice i did not say idle rpms Link to comment Share on other sites More sharing options...
DzNutz Posted February 1, 2011 Report Share Posted February 1, 2011 All the codes tell you is that the value of what is supposed to be put out of a sensor, is out of range. They do not tell you if the sensor is bad. if you replace the sensor after a code is set the ECU should operate like normal again but the code will still be there until the re set is done. This is with the exception of the O2. This is monitored continually which is why you always have an O2 code until the ECU sees it responding within the correct set values. Technically, if you overheat the motor you should get a CTS code because it has gone out of its set parameters for operating correctly (according to the ECU values of normal operation) At least this is what I have gathered about codes for myself. And checking the HVAC and ETACs codes are not harder than the ECU codes. Etacs is another pin and same ground in the Glovebox and HVAC is a plug right by the center on the passenger side. Guess I might have to do a couple tech write ups on checking other codes. Link to comment Share on other sites More sharing options...
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