How to Connect an MPGuino to a Honda VX

[NachtRitter]

Branched off from this (old) thread here: http://ecomodder.com/forum/showthrea...-vx-14029.html

Thought it might be helpful to some Honda VX owners. I can only validate that the wiring works for a 1994 California-specific Honda VX (though I do have the Fed ECU in it right now).

Some helpful pinout information is here: .:FFS TechNet : OBD1 ECU Pin out Schematics :.

Hopefully these pics will help a bit too.

Disclaimer: I prefer reversible mods in general, which applies to electrical mods too. I particularly dislike those "splicing" clips which cut into the electric wires when clamped shut; I've had enough occurrences of those wearing through the wires completely over time that I refuse to use them anymore. And if I don't have to cut and solder, I won't. This approach may not be for you, but that's what I'm showing here.

First, ECU connections. I made the connections I needed for the 'guino directly at the ECU connector.

The ECU is to the right of the passenger footwell (assuming LHD of course). A bit of a bugger to get out so that I could get at the connectors, but it's doable. Service manual pics help:


After getting the connectors off, it's not too tough to figure out which connections you need, based on the images and wire colors given by the reference you linked to above. Each of the three connectors is a distinct size. For example, the VSS signal is included in the "B" connector, which is the smallest of the three. The VSS signal is at pin 10, and should be either yellow with a blue stripe or orange. In my case, it was yellow with a blue stripe (see arrow):


BTW - I had a spare harness, which I used to get these pics rather than dissassembling my footwell again... hope you understand...

You might notice in the pic above that there is an open hinged 'cover' over the ends of the wires... I take advantage of the cover when I 'connect' my wires.

With 22gauge speaker wire, I can strip the ends, bend a little 'nub' into the exposed wire, and then shove it in with the needed connector slot (VSS in this case) (see the white wire in with the yellow with blue stripe wire):


Then I can snap the 'cover' back in place which helps hold my wire in place:


I also used electrical tape to keep the added wire from pulling out any.

I'll leave the Injector Pulse connection as an exercise for the reader. You can use any one of the 4 injector signal wires, which are on connector 'A', pins 1, 2, 3 or 5. You only need one.

Next, constant power. There is a 3-pin Data Link Connector also on the right side of the passenger footwell, just under the glove box. There are two connectors under there; one is the 3-pin connector and the other is a 2-pin Service Check Connector. Service manual image gives you an idea of where it's at (ignore the text about the jumper wire; it's unrelated to this topic. It's the best pic I could find in the service manual that shows where this Data Link Connector is located):


And here's a pic of it in my car:


The connectors are hidden behind the panel normally. The two outside pins of the 3-pin connector are always live; black is ground and blue is +12v. They are protected by a 7.5Amp fuse ( I think it is ) which should be plenty for the 'guino. My connectors are a bit hokey; next time I hit the wrecking yard, I'll see if I can find a standard connector that fits the 3-pin so it looks a bit cleaner.

Let me know if you have any questions...

[blinder]

what a protocol uses your car's obd?

[NachtRitter]

I have no idea ... Honda protocol?

[stewie]

Question on injector cable. Which one works for sure as i was reading few times here that some do no not "power up" so do speak on mpguino so want to make sure i pick one that does. Some people say you can't use ecu injectors (not sure why) but have to use lead from engine bay. Really do not want to do that if i do not have to.

[NachtRitter]

For the injector, the MPGuino is only looking for a pulse, as I understand it. I think any injector wire works on the VX. For some ecu's, I think the pulse might be too high a voltage (?) for the MPGuino... not sure.

[stewie]

NachtRitter thank you. I have a VX as well so it's same ECU. How did you get into ECU, meaning getting the carpet out without tearing it up? Do i have to take off door bottom siding. Any tips? Thanks in advance.

[backsidesnap]

I had an mpguino that was wired in at the points on the ecu, they did not want to stay and it was extremely difficult to reinstall the ecu. so I gave up and just found the diagram online and took the ecu out found the wires, marrked them with tape and then found them on the harness in the engine bay. checked the injector for power. from left to right its the second one. the vss was on the driver side by the brake master cylinder(yellow and light blue I believe) and the most difficult to locate. then just find a ground and a power source and you are golden. Well not really because you still have to snake the wires through the firewall. You can just use a hanger . its located by the battery. then snake those wires to where you want the MPguino to be. I took pictures of mine and will try and post them now if the site will let me.

[stewie]

Sweet please post pics. Love additional guidance. I'm planning to strip rubber insulation with wire stripper without cutting threw the wire few inches away from connector then solder the wire onto wire and tape it with electrical tape. It will stay on this way. I had my injector wires done same way after squirrels eat my injector cables. Works like a charm.

I read someone also ran positive and ground from wires that are in place where clock was/is installed on civics. In VX clock is missing but wiring is there behind the enclosure. Not sure how to get to behind clock. Does it just pop out? It looks like it's solid and don't want to brake dash. Plus i'm thinking to run it cleanly from same location so don't have wires running from all different places.

[NachtRitter]

Hi Stewie... it was a really long time ago and I don't have the car handy for reference right now... but I think you are right; I had to remove the door sill plastic to get the carpet pealed back far enough to reach the bottom of the ecu where the harness was connected. I didn't tear the carpet, but after doing it a few times (replaced the ecu a couple of times due to perceived problems), it started to get easier.

[stewie]

NachtRitter thank you. I really appreciate your help. BTW the plug you 3 pin wiring you have pictures and outline here i found in my 92 honda civic vx to be +5v. My guino would not power up so then i tested it with mulitvmeter and its +5v so it's wired now to +12v but key on only. So next weekend i will either wire it to radio contant on +12v or i found big white and blue and black cable which i belive to be contact power in same spot. I can test it for power however question is are those wires already protected by 7.5 amp fuse or NOT. If not then i can't use it. MPGuino needs to be protected by fuse so it won't fry. Any ideas anyone about those 2 bigger wires if they are protected by fuse or are they before fuse box?