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Diagnosing a SOLID Check Engine Light

A solid check engine light (with service check connector jumpered) is for an internal rom reading error within the ECU. If you receive a solid check engine light on a stock/ unchipped factory ECU, then the internal processor is most likely bad and the entire ECU should be replaced. If you receive a solid check engine light on a socketed/chipped ECU, the following information will help you diagnose and correct the problem.

Four common causes for a solid check engine light on a chipped ECU:

  • Poor ECU soldering of the 28 pin socket/zif or the 74HC373 chip.

  • Poor connection between 28 pin chip and 28 pin socket (bent pins on chip, chip not fully inserted into socket, lever not fully closed on ZIF socket, etc)

  • Chip installed backwards. The notch on the chip faces the ECU wire harness connectors.

  • Incorrect ROM programming on your 28 pin chip. (either corrupt file, or incorrect addressing on chip)

  • Faulty PGMFI main relay. With the ignition in the 'off' position, you should have +12v power at OBD1 ECU pin D1, and no power at OBD1 ECU pin A25 and B1. With the ignition in the 'on' position (key on, engine off), you should have +12v power at OBD1 ECU pins D1, B1, and A25. If not, you may have a faulty PGMFI main relay causing the solid check engine light.

Step One: verify soldering of 28 pin/zif socket and 74HC373 chip

NOTE: If you are working with an HA Motorsports ECU, do NOT remove the back cover to check soldering. This will VOID your warranty. All HA Motorsports ECU's are professionally socketed and tested prior to shipment, and sealed with a warranty void seal on the back cover. If you have checked all other possible causes on this list and your ECU is still under warranty, please contact us for warranty replacement.

To check soldering, remove the back cover on your ECU and inspect for any pins that are not fully soldered. We recommend applying a light layer of solder flux and re-heating all solder joints to make sure you don't have any cold solder joints.

Step Two: Check 28 pin chip connection with 28 pin socket/zif

NOTE: The half moon notch on ALL chips MUST face the ECU connectors as shown below:

Also, be sure if your ECU has a ZIF socket (as pictured above) that the lever is in the fully down position. On applications where a Moates Ostrich is being used for chip emulation and a ZIF socket has been installed, be sure to stack 2-3 28 pin sockets between the ostrich connector and ZIF socket so that the lever on the ZIF can fully close and lock. The ostrich emulation cable's red stripe should face the ECU connectors just as would the notch on a 28 pin chip.

Step Three: Verify that the program burned onto your 28 pin chip is valid.

If using a 512k chip (as in our 27SF512 chips), be sure your chip programmer is set to address the chip correctly. If using a Moates Ostrich, Demon, or Hondata S300, be sure the program is correctly uploaded to your emulator.

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