Assistance wiring db2 engine harness into obd1 db1.

So I am helping a friend bring a formerly stripped db1 back to life and have ran into a bit of a conundrum. I have an uncut db2 engine harness, and a slightly mangled db1 chassis harness. Repairing the chassis harness is not the issue(although it is a bitch), and wiring for vtec is manageable; however, it looks as if the harneses are not quite compatable. I have labeled all of the wires out of the ecu and found most of the problems with the chassis harness, but if I could have more information on the differences in wiring on the plugs that would be great.

Ok so I haven’t been able to find much information on this; however, to begin with there is a 6 pin plug on the driver side main harness that was already cut off of the harness for some reason. I have the 8 pin plug and leads from the passenger side of the harness. It would be helpful if someone could give me the pinouts for these two plugs. Also if anyone could give me the pin outs on the other db2 engine plugs that would be a huge help.

So I have figured out the cabin side of the 14 pin plug found on the passenger side to be as follows.

 [main harness] [14 pin passenger side]

[pin] [color] [purpose]

1: grn/blk Fuel Pump Relay
2: yel/red Oil Pressure Switch
3: yel/wht TPS Sensor Voltage
4: org/blu TDC Sensor
5: wht/blu TDC Sensor
6: wht O2 Sensor
7: red/blu Throttle Position Sensor
8: blu/grn Crank Angle Position Sensor
9: blu/yel Crank Sensor
10: org Cylinder Sensor
11: wht Cylinder Sensor
12: yel/grn Ignition Power Source
13: brn/blk Logic Ground
14: blk/red Logic Ground

and the 14 pin on the drivers side

[main harness] [14 pin drivers side]

[pin] [color] [purpose]

1: yel/blk Ignition Power Source
2: red/yel Air Intake Sensor
3: blu/yel Idle Air Control Valve
4: brn # 1 Injector
5: red # 2 Injector
6: lt blue # 3 Injector
7: yel # 4 Injector
8: red/wht Engine Coolant Temperature Sensor
9: blk Power Ground
10: blu Alternator
11: wht/blu Charging Indicator
12: blk/yel Hot In Start
13: yel/grn goes into capped 3 pin plug by diagnostics port
14: blu tach signal?

and the six pin plug on the drivers side.

 [main harness] [6 pin drivers side]

[pin] [color] [purpose]

1: yel/grn Engine Coolant Temp Sender
2: yel/red VSS (comes off the speedo assembly in the cluster to this pin, not sure why though)
3. wht/grn Engine Oil Temp Switch
4: grn/wht Sensor Ground 2
5: grn/wht Sensor Ground 2
6: org/blk O2 Sensor Heat Control

Now I need to figure out the two engine 14 pin plugs and the 8 pin plug and it should be somewhat straight forward from there on. Please correct me if I am wrong on anything…

Making some progress, comments or assistance welcome.


Taking today off… tomorrow I will.

just starting on the engine harness. Sent my friend off to find a new dash harness as the one on the car was somewhat chopped. Also it seems as if the fan controller is missing and there are some more harness issues. Rednecks and wires do not mix…:bang:

From initial inspection it looks like the plugs have a different pinout and some wires are moved around to different plugs. I am going to start with the multimeter on the engine harness, but they are definitely not matching colors. Tomorrow I am going to cut myself a set of male and female plugs for both of the 12 pin plugs and begin making a set of jumper harnesses. Should be finished decoding the engine plugs tonight.

Good luck, man. I go crazy when it comes to decoding engine harnesses

Sounds like you already figured it out, but it’s not plug ‘n’ play. Your smart move would be to ditch that DB2 harness immediately. It’s only going to cause more problems. They are rare and people will pay decent money for them. Sell it and buy a non-vtec harness. You’ll waste less of your time and even have some cash in your pocket afterward.

What you’re attempting can be done, but it’s pretty pointless, and it’s going to be ghetto and ugly if you make an adapter harness.

Well its for a friends car. I have already gone far enough that I am close to finished, and I am not going to tie any money into it. The harness was already pulled into the firewall by an idiot who thought he knew how to do a wiretuck, so nothing will be visible anyways. The crosswires in the jumper will be loomed back into the harness when I put it back together.

More then anything this is an interesting experience forcing myself to become more involved in the electronics of these cars.

I have done a preliminary breakdown of the db2 plugs, but have yet to get out the ohm meter to double check.

When I settle on a motor for my db1 I am going to scratch build the harness on it and use a single mil spec plug for its entirety, so I see this more as discovery then anything.

finished mapping out the engine plugs except for one wire. I will post of diagrams for the rest once I get the car running. Hopefully tonight.

So on the drivers side 12 pin plug, the engine and chassis harness share the same pinouts for all but three wires.

On the db2 engine harness these are pin 8 (red/blue) knock sensor, pin 9 (yel/wht) vtec pressure switch, and pin 13 (blu/blk) TPS voltage sensor.

On the non vtec db1 main harness they are pin 8 (red/wht) Engine Coolant Temp sensor, pin 9 (blk) Power ground, pin 13 (yel/grn) goes to capped three pin plug on the passenger side by the diagnostics jumper plug.

I am almost finished soldering that side of the jumper, but am stuck looking for some suitable wire for the crosswires to the ecu

your the man.:up:

The list above is not completely correct, but once I get this beast running I will update with the rest of the wiring. Got almost everything finished, but had a brain fart with the reverse lights and coolant sensors/switch so I am going through the engine harness with a multimeter also. I do have the jumper harness finished with the exception of a few wires.

Well I am chugging right along, need to wire in the vtec solenoid, install the steering column, plug in the dash harness and gauge cluster, add coolant, tranny oil, hook up the battery and it should be good to go. Well I mean should be good to run… still have to reloom up the wires and reinstall the dash and interior… Haven’t pulled an all nighter since college, but I want to see this thing run. Fingers crossed…

Good luck. I hope that shit starts, man.

Haha so there wasn’t power to the start circuit… got to check the fuses but I had to take a break after finding that out. I took a power nap and am about to get back on it.

so… the individual who worked on this car doesn’t know how to terminate a ground. I might wait to run new grounds and power wires till tomorrow, but trust me they are hack. loosers ftl. I am going to start a local thread warning of this guy as soon as i find his s/n, but he did the worlds worst wire tuck.

take that bad grounds… still should replace the charge and batt leads as they are not any better but that is a good start.

Well it turns out the battery relocation was junk also, so I am going to need to run a new charge lead and power to the batt; however, the beast is alive… Started it up 10 minutes ago. Turns out the belts are loose so I am going to tighten them back up and see what happens…

yea and did I say it runs…

update, took a quick video. The check engine light is on; however, I only let it run long enough for the thermostat to open up, so the ecu might just need to chance to learn. Either way I will jump and check for codes tomorrow as it is way to late to run with open headers. Excuse the opened harness, sometimes you go to get messy. Once I make sure everything is running properly I will reloom everything.