Location of OBDII port on LT-1?

[ahhudgins]

Originally Posted by frosty

Thanks for the replies, guys.

So, if I get this correctly, I can either purchase the CodeMate code reader for $39 (http://www.rinda.com/marine/marine.htm#merctool), and read the LED flashes to get the MEFI error code (but not know the exact component that triggered the code),
or spring for the USB -> MEFI cable for $195 (http://www.obd2allinone.com/sc/detai...item=mefiscan1) and use the free software (http://www.tunerpro.net/downloadApp.htm) to read the error codes, and much more.

Am I missing anything?

It doesn't look possible to build your own MEFI cable, must be some circuitry involved.

Thanks for the education!

The codemate is the one I bought and modified. The only thing in a codemate is a switch to put the ECM in service mode and a led with a resitor. I mounted my led in the dash so it functions as a check engine light in the normal mode. The way I read it (I'm going to call and check) the $195 is for the cable and the "monitor" software. It doesn't allow any changes to be made as Jim mentioned. The tunerpro appears to be the full blown software for messing up your ECM so it won't run any more!

[ahhudgins]

The codemate is a quick, cheap way to check for a trouble code. This link will also show you the connector.
http://www.mastercraft.com/teamtalk/...=quick+project

[frosty]

Jim,

Thanks for the replies, and explanation!

Originally Posted by JimN

It's not OBD II, it's OBD I and the '98 used the MEFI 2 controller, possibly CEFI 3.

Still more to learn! OBD I is the type of connector, and I am looking for a 12 pin connector that looks like this, correct?



Any idea where this DLC would be located? Mounted to the engine somewhere, or is it one of the multiple capped, loose, wire harness terminations, like the fuel pump relays?

To connect to the OBD I port, would this work?
for $59 (here)

I did check the model # of my MEFI, which in this case ('98 LT1) turns out to be MEFI-2.

Originally Posted by JimN

I wouldn't recommend changing any of the values in the calibration program, if the software allows it. Changing the tuning can result in catastrophic failure if you try to guess.

I would like to be able to read temps, hours ran, etc., and read any error codes should they appear...no reprogramming for me, thank you!
More curious at this point, but I can justify it to myself if I can use it to diagnose a problem if it occurs...

There is also something called an "EFI Diagnostic Adapter" here: http://www.rinda.com/acro/prodlist.pdf
At the bottom of page one, just above the above mentioned CodeMate blinky, is a "#94005 GM-Delphi MEFI 1 - MEFI 4b EFI Diagnostic Adapter" dongle for $39, would this do the same thing as the $59 one above?

[JimN]

Originally Posted by frosty

Still more to learn! OBD I is the type of connector, and I am looking for a 12 pin connector that looks like this, correct?

Any idea where this DLC would be located? Mounted to the engine somewhere, or is it one of the multiple capped, loose, wire harness terminations, like the fuel pump relays?

To connect to the OBD I port, would this work?
for $59 (here)

I did check the model # of my MEFI, which in this case ('98 LT1) turns out to be MEFI-2.

I would like to be able to read temps, hours ran, etc., and read any error codes should they appear...no reprogramming for me, thank you!
More curious at this point, but I can justify it to myself if I can use it to diagnose a problem if it occurs...

There is also something called an "EFI Diagnostic Adapter" here: http://www.rinda.com/acro/prodlist.pdf
At the bottom of page one, just above the above mentioned CodeMate blinky, is a "#94005 GM-Delphi MEFI 1 - MEFI 4b EFI Diagnostic Adapter" dongle for $39, would this do the same thing as the $59 one above?

OBD I is the system, not the connector and while your adapter may work, that's not the same connector used in marine applications. Yours is at the rear of the motor and has a black cover, possibly with some gray on it. It should be near the circuit breaker and it's easier to get at it if you release the gas struts on the motor cover from the brackets on the floor.

The cheap code reader will show only the codes, not actual data. Showing only codes is fine if you need to diagnose a problem but the data lets you see if something is out of range, although you'll need to find out what the correct range is, in order for that info to do any good. For example, the TPS will indicate a voltage and a percentage- if the throttle position indicated is 2% and you're at WOT, it means the TPS is either the wrong part, or it's defective. The reason I mention this part specifically is because your motor won't work with the TPS from most of the rest of the GM engine lineup.

[frosty]

Originally Posted by JimN

OBD I is the system, not the connector and while your adapter may work, that's not the same connector used in marine applications. Yours is at the rear of the motor and has a black cover, possibly with some gray on it. It should be near the circuit breaker and it's easier to get at it if you release the gas struts on the motor cover from the brackets on the floor.

Thanks for clarifying that for me, I will dig around & look for the connector next month when I get some quality time with it!