Thread: To OBDI or Not to OBDI

Who said anything about cutting the stock harness? I used plugs from a third crappy harness and converted the OBDI harness. I had the factory harness and could go back at any time.



Step downs, to me, seem like another point of failure. You are putting another connection in the chain. Also, you have to destroy an ECU and another harness to make one.

The injectors come off of the engine harness, and actually there is only one connection to the engine bay harness. Nissan basically put two harnesses in one, the starter power wire, the coolant temp sensors, and a few others run along with it. If you pull that harness apart the wires are separate. This also helps clean up the bay.

You don't "have" to destroy another ECU or harness to make them... you can buy one which has all brand new parts and no splices between the harness and ecu plugs.

I use them ALL the time with Hondas and the failure rate is ridiculously low if you buy a quality harness.

I bet I have had 1 fail out of the box in the past 6 years!

I am working on trying to get a more affordable option for these things, but without the demand for them it is kind of tough, since the parts for the connector sides are a little more expensive than most. I am using on on my B14 VE project in a week or so and will post up some more info when I have it running.

Ok, so you said something about cutting "A" stock harness, not "THE" stock harness

They are another point of failure, and I don't know if I can trust my solder work . Though my AMP bypasses (had to steal the plug from a Bose AMP) are still working perfectly fine

My final straw for ditching the OBD1 harness idea was the firewall hole. P11's hole is MUCH bigger then the OBD1 one. Thus I would have to figure out a way to fill the gap, etc. etc.

Exactly why a step down is right up your alley way.

If you do them right they are fine. Most people do not buy new connectors and crimp their own pins. I would never solder one together with used connectors, which is how 98% of the people who make their will do it.

Where do you get your harnesses from? Not many people make them for Nissans.

Just a fun fact, doesn't seem like 32bit ECU's have a relay. If they do it's not ontop of the ECU.

32bit as in a B13/OBDI? If so, there should be a green relay attached to it unless it doesn't have the side metal casing/rails attached to it (which the relay attaches to).

I done both of these! I swapped in a b13 harness/engine into my buddys b14 200sx and it was a pain in the ass. It was not just a simple pull out and replace the harness. You also have to splice in wires for the tach and all gauges etc etc... not fun..

Now with my b14 200sx i made a step down harness MYSELF. Its so easy undo also.. My opinion its the best way if you get a QUALITY step down adapter. I covered the whole end in epoxy.. pretty much bullit proof..

32bit is the B15/P11 ECU's, the B13/B14 ECU's are both 16 bit.

Edit: I thought OBDI ECU's where 8 bit, turns out both OBD1 and B14/P10 OBD2 ecu's are 16 bit.