2G OBD2 ECU connection problem

[Karhuisa]

Hello. So my 95 Eclipse has this weird issue. I bought a cheap bluetooth OBD2 scanner so i could check why the ABS light is on. Well, it just said that "connection with ecu failed". I thought it was the cheap scanner, so I bought a more expensive one. Didn't work either, same message connection with ECU failed. Well, today I went to closest auto repair shop and they scanned my car with latest and probably best scanner out there, same problem.

I have checked every fuse, all the wiring seems fine, I measured the voltage on the 16th pin on the OBD port, and it shows over 14volt. I have run out of ideas, if all the fuses are good, wiring good, and the port gets power. One thing i have to try is taking the pins out of the OBD2 connector and squeezing them little bit if they have become too loose to make contact.

If anyone have had same issues i would be so glad to know how to fix this.

 

[pauleyman]

I think you're on the right path Check each pin/wire

 

[luv2rallye]

Also check that pins 4 and 5 have continuity to ground.

 

[Dihtung Glava]

Hijacking this thread

I checked pin 16 on my OBD port - it has 12V, I checked pin 4 for ground - that's good. I also checked that all the pins from the 3rd plug on the ECU are where they need to be and the fuses are good. Tried 2 different OBDII scanners, a cheap one and a licensed one, they wouldn't connect.

I'm not getting continuity between the pink wire on the OBD port and the pink wire at pin 62 on the ECU, are those supposed to be connected? I figured I would check this connection;

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but I can't find it under the dash... anyone know?

I'm scheduled to try out a Mitsubishi dealer's scan tool next week to see if that works, is there anything else I can try until then?
Thanks.

 

[luv2rallye]

- OBD port pin 5 (signal ground) must also go to ground.
- Yes there must be continuity between the pink wire on the OBD port and the pink wire at pin 62 on the ECU. That's the main OBD2 signal wire (K-line).
- J/C 2 is a special 33 pin jumper connector (where different wires get jumpered together) which I think is above the clutch pedal.
- At least here in the USA, the pink wire from J/C 2 (B-08) pin 23 to ECU pin 62 goes through another connector B-63 pin 18 (although I see that's not shown in your diagram so maybe yours doesn't).

 

[Dihtung Glava]

- I have ground on pin 5 on the OBD port
- I DON'T have continuity between the pink wire on the OBD and the pink wire on the ECU
- I cannot find the J/C 2 connector, I might have to pull the dash again
- I do have B-63; it's the middle blue one, behind the radio - that thing has continuity from the ECU pin 62 to pin 18 on the connector, but not from pin 18 to the OBD. The wire also switches from pink to orange through that connector so I guess I'm looking for an orange wire now??

EDIT: found J/C 2 connector, describing it with a "cabin coordinate sytem": it's above the brake pedal and behind the gauge cluster;

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...all 3 pink wires have continuity between themselves and the OBD port so I think that's good, right?
Also, here's a picture of B-63 while I'm at it:

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I marked the orange wire (pin 18) that connects to the pink comming from ECU pin 62. No continuity between that and any pink wires at the OBD or J/C 2.

 

[luv2rallye]

Ok, your problem is you don't have continuity from ECU pin 62 (or B-63 pin 18) to OBD pin 7 (pink wire). I don't know why your wire switches from pink to orange through that connector - if it's just faded, or cars in your part of the world are different, or a previous owner put in a different harness, or your diagrams just don't show all non-vital connections (since it doesn't change the destination), or the connector pin isn't locked so it gets pushed back when plugged in, or what. But I have the real 1999 factory Mitsubishi Eclipse North America diagrams (not some AllData or other ones) which does show that pin 18 connection. Granted it shouldn't make any difference that it goes there but it is different than the diagrams you have. See attached.

What I'd suggest is temporarily connect a wire from OBD pin 7 (pink wire) to either the ECU pin 62 or B-63 pin 18 to see if your OBD scanner then works (to verify that is the area of your problem).

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[Dihtung Glava]

Thank you, solid info everytime.
The wire pictured isn't faded, it's legitimately orange. I spent the better part of my sunday trying to see where it goes without removing the dash.

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I tracked it to this box above the steering column. The part number on it doesn't give much on google, just one or two of these units for sale with "alarm" somewhere in the description. I can't find it on any wiring diagrams either so I think it's a European anti-theft thing?

Since it's not doing anything, I might just leave it unplugged and jump the pink and orange wire with a paper clip at the connector and see how that goes.

 

[luv2rallye]

Ya, MR309675 is listed as a theft control unit here:

MR309675 - Control Unit, Theftproof Mitsubishi Direct Parts

Genuine OEM Control Unit, Theftproof Part# MR309675 Fits

www.mitsubishidirectparts.com

 

[Dihtung Glava]

Well, as far as I'm concerned, this is resolved.
I jumpered the pink and orange wire going into the anti-theft box at the connector and I'm reading continuity between ECU pin 62 and OBD pin 7 now. Don't look at my makeshift jumper too close - It's temporary.

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The licenced OBDII scanner is able to read my diagnostics now, I haven't tried the cheap one yet. I figured I could do this everytime I need the OBD port and keep the European anti-theft computer thing plugged in the rest of the time, but the car works normally even with it unplugged, so It might just get escorted off the premises that are my cabin.

Thank you @luv2rallye for all the help and confidence, @Karhuisa you can have the thread back now

 

[luv2rallye]

The J/C (x) "jumper connector" is typically used to activate different options/wiring used in different markets of the world. That way Mitsubishi can use the same wire harness in all markets of the world and just change the jumpers. So I think your European anti-theft control unit may be one of these cases.

 

[luv2rallye]

I found a European diagram that shows your pink going into an orange on B-63 pin 18 on its way to the immobilizer ECU (which North American Eclipse's don't have):

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[Dihtung Glava]

How in the world did you find this hahaha
I don't know what the symbols inside the immobilizer mean... can you make out what conditions have to be met for it to connect pink and orange?

 

[luv2rallye]

Only the output transistors are shown which when turned on, will ground OBD pin 7 preventing any communication through the OBD port (presumably to prevent hacking through it). However you can't tell what turns them on as the rest of the circuit isn't shown. Perhaps a European Mitsubishi Eclipse Technical Manual might describe how the immobilizer works.