Question about 1994 Chevrolet Caprice Classic

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My 2004 suburbans check engine light is on can't read codes withobd1 anylizer

Why can't my obd1 read codes

Posted by Anonymous on


5 Related Answers

Pierre Laplante

  • 2042 Answers

SOURCE: 1997 suburban sevice engine light came on

insufficient switching bank 2 sensor 1 that mean the oxygen sensor on the passager side dont change voltage fast enought remove clean it or if it old change it hope it help FIXYA OUR POST thanks pierre

Posted on Jul 12, 2008




  • 103 Answers

SOURCE: 2004 colorado code p0172

check your gas cap. If you fill your gas while the vehicle is running, it will also cause your light to come on. Go to OReilys or Autozone and they will shut it off for free and tell you the problem

Posted on Jul 25, 2009



  • 1985 Answers

SOURCE: 2004 chevrolet suburban intermittently displaying

you need to check fluid level in radiator,low coolant will cause your problem,but fill the resivour too,
you need to see if you lost fluid first,then check fan operation,

Posted on Dec 09, 2009

Lyle D. Rowh

  • 743 Answers


The only way those type of scanners will give you a code is if it is a hard code. When a check engine light is on, but doen's flash it is usually referring to an emission problem. A flashing light refers to misfire. Spark plugs, wire, etc. A snap on scanner or Genesis Scanner is able to look at perimeters inside the system which is a better approach when you don't have a hard code. Sometimes after the code is on long enough it will become a hard code and the type of scanner that you have will pull it. The thing that often happens is the EGR isn't circulating properly and you get an intermediate light and don't get a hard code for a while which leaves you in the dark. You might take your vehicle to a local service shop which uses a better scanner and they can look at what is going on and solve that problem.

Posted on Mar 07, 2010

Testimonial: "You are correct. However I'm not enen getting the code 12 that the system is working. I think my computer might be fried? "


Duane Wong

  • 6826 Answers

SOURCE: How to check out the codes on check engine light a

1988–95 MODELS Listings of the trouble for the various engine control system covered in this manual are located in this section. Remember that a code only points to the faulty circuit NOT necessarily to a faulty component. Loose, damaged or corroded connections may contribute to a fault code on a circuit when the sensor or component is operating properly. Be sure that the components are faulty before replacing them, especially the expensive ones. Fig. 1: ALDL connector — 1988–92 models 84904060.gif
The Assembly Line Diagnostic Link (ALDL) connector or Data Link Connector (DLC) may be located under the dash and sometimes covered with a plastic cover labeled DIAGNOSTIC CONNECTOR.

  1. The diagnostic trouble codes can be read by grounding test terminal B. The terminal is most easily grounded by connecting it to terminal A (internal ECM ground). This is the terminal to the right of terminal B on the top row of the ALDL connector.
  2. Once the terminals have been connected, the ignition switch must be moved to the ON position with the engine not running.
  3. The Service Engine Soon or Check Engine light should be flashing. If it isn't, turn the ignition OFF and remove the jumper wire. Turn the ignition ON and confirm that light is now on. If it is not, replace the bulb and try again. If the bulb still will not light, or if it does not flash with the test terminal grounded, the system should be diagnosed by an experienced driveability technician. If the light is OK, proceed as follows.
  4. The code(s) stored in memory may be read through counting the flashes of the dashboard warning lamp. The dash warning lamp should begin to flash Code 12. The code will display as one flash, a pause and two flashes. Code 12 is not a fault code. It is used as a system acknowledgment or handshake code; its presence indicates that the ECM can communicate as requested. Code 12 is used to begin every diagnostic sequence. Some vehicles also use Code 12 after all diagnostic codes have been sent. Fig. 2: ALDL connector — 1993–95 models 84904061.gif

  5. After Code 12 has been transmitted 3 times, the fault codes, if any, will each be transmitted 3 times. The codes are stored and transmitted in numeric order from lowest to highest. NOTE: The order of codes in the memory does not indicate the order of occurrence.
  6. If there are no codes stored, but a driveability or emissions problem is evident, the system should be diagnosed by an experienced driveability technician.
  7. If one or more codes are stored, record them. Refer to the applicable Diagnostic Code chart in this section.
  8. Switch the ignition OFF when finished with code retrieval or scan tool readings. NOTE: After making repairs, clear the trouble codes and operate the vehicle to see if it will reset, indicating further problems.
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Posted on Jul 12, 2010

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1 Answer

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If it has OBD2 you'll need a scanner or code reader. Most auto parts stores will check OBD2 for free in hopes of selling you some parts.
You can do an internet search for OBD1 codes and see if the connector plug looks like yours. If it does you can use a paper clip to jumper two connectors and make the warning light flash.
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