Make a Marine EFI code tool for less than $1.00
 

Some of you may know this trick, but I thought I would share it in hopes that it helps some folks. It is very easy to make a simple, but very useful, Marine EFI Code reading and clearing / Base Timing Tool. And you can make it for under $1.00!

Materials needed:

One 12volt resistor type LED light
One small paperclip cut in half

That’s it!

This home made code tool works every bit as well as the one I paid $50.00 for. It will work on most 1993 to 2000 marine EFI systems with the ten pin Data Link Connector. This includes Mercruiser, Volvo, Crusader, PCM, Indmar, and a few others.

How to hook it up:

1) Ignition key “OFF”

2) Remove the cap from the Data Link Connector (DLC)

3) Slide the LED into the female terminals of position E and F on the DLC, making sure that the positive side goes into terminal F and the negative side into terminal E. No damage will occur if you get it backwards, it just won't work.

4) Turn the ignition key to the “ON” position. The LED should come on steady.

5) Insert the half paperclip into terminals A and B – This puts the engine in “Service Mode” and codes will begin to flash on the LED. On 1996 and earlier engines you may hear the fuel pump come on. If not you should be able to hear the Idle Air Control (IAC) motor move. Use care in this step, do not insert in the wrong terminals or ECM damage could result! Look closely, the terminals are clearly marked.

6) Read codes by observing LED flashs. If the self diagnostic system is working it will flash code 12 – one flash, pause, two flashes, long pause – it will repeat three times. If other codes are present they will flash in order of lowest to highest. Continue to read codes until the code 12 sequence is repeated.

You can also be clear codes (by moving the throttle to 100% and back) and set base timing while in Service Mode.

Dave

Update

Just wanted to add that a computer safe test light can be used instead of a LED. As common as LED's are, I don't think most people have them laying around, but you may have a test light.

Anyway, when using a LED, the ECM supplies constant 12+ to terminal "F" providing power to the LED, and then the ECM flashes the LED by closing the ground circuit on terminal "E".

To use a test light instead of a LED, you would provide power to the light by connecting the alligator clip to a 12v+ source (engine breaker, starter, battery, or whatever is an easy place to connect). Then you would (still using a paperclip to jump terminals "A" and "B"), touch the probe end of the test light to terminal "E", and the light should begin flashing.

Again, the test light must be the type that is approved for use on computer circuits. A non-approved test light will not work and could even damage the ECM.

Re: Make a Marine EFI code tool for less than $1.00
 

That is amazing. Now how in the heck did you figure all of this out? I'm thinking of lots of cooked ECMs and smoke and melting wires in the "trial period". Either way...thank you for the info!

Re: Make a Marine EFI code tool for less than $1.00
 

youc an buy a tool that does exaclty the same thing for 40 bucks, just a matter of checking the pin locations and building your own redneck version. I beleive you can even get the plug from GM if you wanted to make a realy fancy one for 10 buvks, Thanks for shareing the info with ud all though, now we don't all have to buy the 40 dollar tool :D

Re: Make a Marine EFI code tool for less than $1.00
 

Shorting A and B with the paper clip also sets it in base timing mode, in case you want to check your timing while you are at it ;)

Re: Make a Marine EFI code tool for less than $1.00
 

Great trick........now, how do you find out what the flashes mean? Is there a list somewere?
Thanks

Re: Make a Marine EFI code tool for less than $1.00
 

Dave1972,
It reallly wasn't that hard to figure out, but I did my homework before I tried it. No fried ECM's to date. The next step was to build it into a connector. See picture below.

DanB,
Below is a list of MEFI trouble codes that I compiled.

Dave

Re: Make a Marine EFI code tool for less than $1.00
 

Thanks for the info........Is that a pic of the Plug tool you paid $50 for?

Re: Make a Marine EFI code tool for less than $1.00
 

DanB,
No, thats the code tool I made using a 10pin connector body. It's just a step above using the bare LED and paperclip.

Dave

Re: Make a Marine EFI code tool for less than $1.00
 

it looks just like the one you can buy for 40 bucks, except I think that one had a red LED. that's pretty cool how you mounted the LED nice and clean like that.

Re: Make a Marine EFI code tool for less than $1.00
 

Does this timing procedure also work for the 5.7L vortec MPI ?
ie. same DLC and pin locations (A&B)

Blake

Re: Make a Marine EFI code tool for less than $1.00
 

Blake,
If it has the 10pin Data Link Connector (like the one shown in the picture above), it should work.

Dave

Re: Make a Marine EFI code tool for less than $1.00
 

Dave,

How about MEFI 4 systems. If it works, are the error codes the same?

Greg

Re: Make a Marine EFI code tool for less than $1.00
 

Dave can you please PM me!

Re: Make a Marine EFI code tool for less than $1.00
 

Frequency,
It will work on MEFI4 systems. The codes are the same for the most part, but MEFI4 systems can have multiple sub-codes under the same number that can differ depending on the engine (see example list below - from Volvo 8.1 ).

Kilroy,
You have a PM.

Dave

Re: Make a Marine EFI code tool for less than $1.00
 

Do you know the pn for the connector you used?

Re: Make a Marine EFI code tool for less than $1.00
 

The connector is a Packard "Mertri-Pack" 150 series sealed 10 pin male connector. In addition to the connector body you will need the TPA (grey thing that clips to the top), terminals, seals, and (optional) plugs.

Info on Metri-pack connectors:
http://www.powerandsignal.com/IDC/Pr...MetriPack.aspx
Click on "2003-04 Global Connection Systems Catalog -- Metri-Pack 150"

Dave

Re: Make a Marine EFI code tool for less than $1.00
 

Dave,
I am having a hard time finding the DLC connector. I have found the transom harness connector (10pin) and the CAN connector.
Is it located near the distributor or ECM? this is on a 2003 mercruiser 5.7L vortec

Thanks,
Blake

Re: Make a Marine EFI code tool for less than $1.00
 

Your engine has an ECM 555 controller. This trick will not work on PCM or ECM 555 systems. You will need a scan tool or smartcraft system display to read faults. :(

Dave

Re: Make a Marine EFI code tool for less than $1.00
 

does this also mean I can't set the timing unless I have a scan tool?

Blake

Re: Make a Marine EFI code tool for less than $1.00
 

Blake,
You can't set the timing at all. Base timing is controlled by the computer and is not adjustable. You can loosen and turn the distributor, but it only aligns/misaligns the rotor with the distributor cap, it does not change the timing.

Dave

Updating Link
 

Just wanted to update the link and add part numbers

http://www.powerandsignal.com/docs/Catalog/met150.pdf
(page 17)

black tower cover (my name for it) PN - 12045808
TPA PN - 12124264

Not sure if they still sell to public but I'm calling Monday to see. Thanks for the original info.

So then when I hook up the paper clip to A and B term. then I can start engine and set base idle?

I would start the engine first, if it's a MEFI 1you will need to increase the RPM to around 1600 before you put the jumper in. If it's MEFI2 ,3 or 4, you just start the engine and put the jumper in, the RPM will automatically increase. Then set the timing.

Dave

I have to disagree with this. Turning the distributor sets the base timing when in service mode. In normal operation the computer or ignition module controls the amount of advance.

Rene

You are correct if your talking about a MEFI (pre 2002) engine. I was referring to the later model ECM555 engines that do not get the ignition reference pulse from the distributor, they use a crank and cam sensor. So turning the distributor will not change the timing and there is no Service Mode on these systems.

Timing
 

So how do I tell what MEFI I have on a 1995 Baja caliber twlight with 350 mag? And in order to adjust advance timing I need a scan tool or no? What is the must I can advance timing too? Thanks for the help

Dave:
Just thanks for posting.. :-)

For information on how use a test light instead of a LED to read trouble codes, see update of the first post in this thread.

Dave

code reader reads zero.
 

hi dave.

looks like you know a lot about efi's.

i made that tool that you explained us, but in my case with the engine off, just the key on, i have code 12.

my boat is a monterey 98 5.7 efi digital ignition, still misses and backfires on top speed, i already checked everything possible and changed, with no success.

should i plug the tool with the engine running? or buy a better scan tool to find the codes, or i dont have no codes and the problem gotta be something else?

thanks

Make a Marine EFI code tool for less than $1.00
 

does this work for a 2005 mpi 5.o

No only 93-2000

dumb question what takes it out of service mode do you just pull the pins out or is there a procedure? I have heard of early models sometimes getting stuck in service mode.

This was written to address the MEFI 1 through 4 family of controllers ONLY. And no you can not inadvertently stick the ECU in service mode.

Works like a charm really simple thanks for this!

I did try to clear the codes using the throttle and it didn't work. I pushed it to full throttle then back to idle and then pulled the pins out.

Key off
insert A to B jumper
Key on Engine off
Full throttle then return to idle
Key Off
Pull Jumper

Optional fire extinguisher not included :D

Awesome thanks!

great info , but how do you remove it from service mode?