Hardtop Wiring Sub harness: 4pin to 3pin conversion - S2KI Honda S2000 Forums

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Hardtop Wiring Sub harness: 4pin to 3pin conversion


Old 03-10-2012, 04:36 PM
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Default Hardtop Wiring Sub harness: 4pin to 3pin conversion

Installed an OEM Hardtop over the weekend and ran into some issues.

Background info:
The car having the install is a 2007 s2000 with the 3 pin body connector for the hardtop subharness. The hardtop came with the strikers, catchers, and latches so those were good to go. An order was placed for the remaining parts: hardtop brushes and hardtop sub harness. The order was placed through hardtopguy since they had everything that was needed. The parts came in and it was time for the install.

Even though you specify what year your car is when ordering from hardtopguy, the wrong harness was sent. I have a 4 pin harness in hand to install on 3 pin body harness. Great. I tried contacting hardtopguy via email and phone with no luck. Personally, I'm not really happy with the experience from the site. Oh well. Time to do some digging and figure this out.

Looking through forums I couldn't find the information I needed to get this working. I obtained access to Alldata, the wiring diagrams, my box of old honda wiring, and got to it.

4pin to 3pin Conversion:
The car having the installation had the 3 pin connector on the harness behind the driver seat.

The three wires on the vehicle harness are as follows: Green (Rear Window Defogger Change Relay), brown (Defogger +voltage), and black (ground).

Looking at this connector and having performed many honda swaps throughout my days, the connector looked familiar. I grabbed my box o' honda wiring and sure enough it is the same as a vehicle speed sensor from a D/B series. I removed the connector from an engine harness and it plugs directly into the three wired hardtop connector.

The 4 wires on the hardtop subharness are as follows: Green (Rear Window Defogger Change Relay), Black/Red (defogger +voltage), Black/Yellow (Rear Window Defogger Change Relay relay ground), and Black (ground).

On cars with the 3 pin connector, the hardtop subharness Black/Yellow +voltage wire is not needed at all. Earlier AP1s needed a bit of extra wiring for the defogger relay to change between the softtop and hardtop window. Newer bodies are actually prewired for this situation. (thanks honda).

The hardtop defogger plug had only two wires on the outer terminals of the plug Brown (+voltage) and Black (ground).

Depin the 3wire vehicle speed sensor plug you salvaged and the 4pin connector on the hardtop subharness.

You now have an empty 3pin VSS plug that will plug into the vehicle body harness. Insert the loose terminals from the hardtop subharness into the VSS plug.

Match the wires:
Body plug | Hardtop Subharness
Green > Green
Brown > Black/Red
Black > Black

**The Black/Yellow wire on the 4pin hardtop subharness is not used on a car with 3pin body connector.**

You can take it a step farther and remove the Black/Yellow wire from the sub harness as I did. However, the hardtop defogger plug had only two wires in the connector so you can just leave it there if you're lazy.

After performing this simple conversion, I now had the 3pin hardtop subharness I needed without ordering another or waiting for hardtopguy (who still hasn't returned any contact). With my harness connected and the hardtop installed, the roof switch is disabled and the rear hardtop defogger is working fine.

These steps worked for me in this instance. Mission accomplished.
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Old 01-14-2017, 10:49 PM
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Great write up this saved me a lot of trouble and a good amount of money , going to wire up my hardtop defroster tomorrow
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Old 01-29-2017, 08:54 PM
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great writeup! thanks alot for this one......
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Old 02-01-2017, 06:34 AM
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Nice write-up. While not defending the wrong part or excusing the lousy service I guess maybe be happy you got a harness at all and had something to work with. The 3-pin harness has been discontinued from Honda and impossible to find at original prices. I thought about attempting this as well with the 4 pin which came with my used top but as I have more money than time at the moment..... I paid $150 for one off of ebay....wish you had posted this a tad sooner!
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