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Discussion Starter #1
Background:
D16a6 running as OBD1 using
D16z6 harness, intake manifold/TB/Injectors etc
D15b7 distributor
test idling on stock p28

In the beginning of this build I was going to use a d16z6 (still plan to eventually) so I wired a vtec light into my car for verification. I've had vtec engagement trouble on these 1 and 2g honda retrofit swaps before so I did it as a diagnostic tool.

I tapped the light into the wire going from A4 to the solenoid (I have triple checked this wiring).

Anyway, I'm using a stock p28 to start up and run the motor while I'm checking for leaks etc, before I pull the motor back out to finalize everything/paint the bay etc.

Since the motor is a d16a6, there's obviously no vtec components, but the harness is from a d16z6 so the vtec plugs are just dangling currently.

Funny thing is, the vtec light is on each time I run the motor.

Why is the light on?

I've triple checked the wiring. Why would not having a pressure switch or solenoid installed cause my vtec light to come on?

Is the pressure switch/solenoid normally closed (circuit wise, not mechanically), and therefore since I don't have either the computer thinks vtec is engaged? Do I need to jump/ground something?

Looking for some ideas here. What am I missing/forgetting/screwing up.

Please don't turn this into a vtec light argument thread. I'm looking for some help here.
 

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Discussion Starter #2
See pic - motor idling, just started it up.

No oxygen sensor installed, running rough - but shows vtec is engaged??? (LED right near the tach)
 

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96,97,00 civic
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what head are you running?

I think you're on to something with the closed circuit idea, and if that was the case you could just close the circuit yourself! For a simple fix you could obviously pull the bulb or run a non-vtec ecu.
 

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Discussion Starter #4
It's a d16a6 head as well. It's a complete a6 aside from the obd1 IM/TB/electronics.

I want to jump the connector to test if the light will go off but I don't want to risk anything until I can confirm how the vtec wiring is (open circuit vs closed circuit).

I can't tell much from the info I can find online except the mechanical aspect of the switch and solenoid.
 

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pull the VTEC solenoid plug in the engine bay and measure resistance between the pin on the solenoid and ground. my guess is that it's not fully open and has some resistance. that's how the ECU can figure out a broken connection. the resistance is probably insufficient to keep your LED off.
 

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Discussion Starter #6
Does A4 from the PCM send a ground signal or a 12v signal?

I think the problem is in my wiring after all. I noticed a mistake I made on my CEL light.

My CEL light hasn't been on at all (even though certainly the car should be throwing all sorts of codes), so I started checking and noticed the PCM provides a ground/closes the circuit for the CEL coming out of A13. I had my gauge cluster wired up for the PCM to provide a 12v signal.

I'm thinking I might have the opposite problem on the vtec light?
 

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ej8
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What ecu?

And the led uses low volts and they can glow just from having 1 volt on the wire. This doesn't mean vtec is on.

Get the connector and check it with a voltmeter and make sure there is 12 volts there.

Also vtec shouldn't kick in without the pressure switch reading ground.
 

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If your VTP is not hooked up and wired as per factory specs, once you enter VTEC, you are stuck on secondary maps.

With no wired in VTP or VTS, you should see a 'soft CEL' which can seem to be a solid CEL.

If vtec is locked on 24/7, regardless of the above, make sure you aren't using an LED test light that has no current limiting resistor, because I believe there is a pullup on the VTS circuit to check for ground thru the solenoid thus satisfying the VTS CEL routine.
 
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