If your Harlan RPM switch has flaked out, can you answer some questions for me? I'm trying to pin-point the most reliable/unreliable setup:

1) Where's your 12V coming from?

2) Relay?

3) RPM signal?

4) Do you have a way of watching the switch activate ALL the time to verify it works?

5) How often and when does your switch flake out?


I'll go first:

1) dashboard fuse box
2) no
3) coilpack as of yesterday
4) yes
5) about every 15-20 times of use, usually failing when I barely hit the switchover and then change a gear.


I have a hard time believing that the switches are flaking out because of where the RPM signal comes from. I think the problem lies within the activated ground of the MAP switch. Regardless of whether or not the RPM switch is run with or without the relay, it seems like most people are having problems of some sort. Some say that they have no problems at all, which I have hard to believing especially if they can't view the activation of the switch's LED.

My Harlan shiftlight has been flawless for 2 years now, but the difference in the shiftlight and the rpm switch is that the shiftlight only turns on a big LED, it does not activate a ground on a 12V system.

I don't quite understand electric currents and such, but I think there is a definate correlation between activation of the ground on the MAP switch. I don't know if some sort of current or current spike ends up going through the RPM switch and flaking it out or what? Is there anything we could do?



Dave

 

Electronically providing a ground is providing a ground. Grounding a LED, relay, MAP switch, or buzzer are all the same to the Harlan. By convention we talk about current flowing from + to -, so the current from the battery flows through the MAP switch (or whatever) through the Harlan to the ground of the Harlan. That's why it can only sink .5A of ground; if you tried to ground something that used a lot more current it could fry components of the Harlan.

I still don't see why you have a problem, but there's only so many things to trouble shoot. Harlan 12v, ground, Rpm signal input, output. Has there ever been a case where your Harlan activated, but your VI didn't activate?
-hype

 

1- 12volt source = Cig lighter
2- Relay = Yes
3- RPM Signal = Tapped into wire for Coil #1 on ECU harness
4- Visual = No
5- Flake Out = Only on 5k rpm setting, once every 15 times engaging in first gear, and it has not opened only one time in second gear.

It has not opened a total of maybe 5 times total. when it does happen, i will mash it through first gear, it doesnt open, and then when i hit the 1-2 shift, then rpms land at or near the VI engagement and i feel it open.

also, i have my harlan located under the shifter console so i dont think heat is a problem.

i know this isnt the case...but it feels like i go through first too quickly for the RPM switch to read. like it just flies by and it catches up in second gear. thats the feeling i get.

i wonder if it has anything to do with the cylinder settings on the Harlan. you can choose your number of cylinders (i.e 4,6,8...) or you can use the "coil per plug" mode. i use the coil per plug mode. i havent tinkered with switching it to 6 cylinder mode to see if it does anything differently.

--Paul

 

Has anyone used the TAM screw on the back of the speedo gauge pod?

 

Is there a way to hook up a manual override type switch? If you're in a race situation you could flip the switch on to provide ground if the RPM switch doesn't go off.

 

Quote:

I still don't see why you have a problem, but there's only so many things to trouble shoot. Harlan 12v, ground, Rpm signal input, output. Has there ever been a case where your Harlan activated, but your VI didn't activate?
-hype

Last night I wired the switch to the coil, checked EVERYTHING, verified all my connections were good and soldered, verfied I had a strong ground, etc. It works right now, but I don't have any faith that it will work 100% of the time and that bugs me a lot. People are having the switches flake out regardless of if they're hooked to the coil or the ECU.

I can tell when my VI is not opening because I can't hear it. If I've got it set anywhere between 4500-5500rpms, the change in intake pitch is quite noticeable. It seems the switch flakes out in 1st or 2nd gear, usually 2nd gear for me. This seems to be the case for a lot of other people too. Many are now watching there RPM switches and are noticing that there are problems even though they thought it was working flawlessly before.

As for hooking up to the tach TAM screw, that's just too much of a pain. Wiring to the coil is a lot easier.



Dave

 

Dave, I am in no way saying that you aren't having problems. I helped install other VIs, and one (a 96) has Harlan problems. He gets the blinking Harlan after so many correct operations like I believe you mentioned once before.

Again I'll ask: Has there ever been a case where your Harlan activated, but your VI didn't activate?

Regarding the TAM: It's the same as tapping the ECU wire. On '99s there is no TAM screw, and tapping the ECU does NOT work. On 95s you can run 1 Harlan at most before you have tach problems.

I wonder how many here have Harlans under their hood.
-hype

 

Yes, I did this when I was waiting for my Harlan replacement switch and I had already scheduled a dyno so I needed a way of activating the switch. I'm seriously considering on wiring my bypass switch back in so I'll get consistent runs at the track. I figure all I have to do is splice into the MAP ground that is connected to the RPM switch effectively bypassing the Harlan when needed.

I figure you try your luck and hope it opens in 1st with the RPM switch and when you hit 5200rpms in 2nd, hit the switch and leave it on. Assuming you've got the JWT ECU, you're 2-3 shift should land at an indicated 5100-5200rpms which is why leaving the VI open should be perfectly ideal.

If anyone is a electrical guru, please look over what I said above and let me know if I'm right in my assumptions about bypassing the Harlan and that I won't fry anything.



Dave

 

I have to wire mine in about 3 days...waht do I do

-matt

 

1) Nope.

2) The RPM switch has always been in the cabin, not under the hood.


Dave

 

The only time my Harlan didn't work was when the ground wire came loose due to a poor soldering job.

1) Cig lighter
2) yes
3) no. 1 coil
4) no
5) don't know if it ever has other than when the ground wire came loose. When I test it with the hood open so I can watch it, it never fails to work. I can't tell by the engine sound when it engages. Being supercharged the intake path is so much longer than NA that there is basically no noticeable change in pitch.

 

1) Battery

2) Yes, Relay

3) #1 coil

4) No, but have done 28 Dyno runs while watching it, and often test it just to be sure with the hood up.

5) Never flaked out that I've seen. I know I would feel it if it did flake out.

6) Mine is under the VI Cover, in the engine bay.....heat has never caused a problem.

 

How come nobody uses the tach screw for the RPM? Everyone uses a coil. I don't even know how to do any of that. Mine will be wire to battery and probably tach because I don't have a clue on how to wire it to a coil.

 

Tapping to the coil is easy. You find the harness going to the number one coil. There are three wires in the harness, two are solid colored and one is striped. You scrape some insulation away from the striped wire and solder a jumper wire to it. The other end of the jumper goes to the tach signal wire of the Harlan switch.

 

I went ahead and wired in a manual bypass switch to engage the VI when needed (I'll definately use it at the track).

I did notice something very interesting, if I flick the manual switch multiple times in a row, sometimes the Harlan RPM switch LED will begin to flash just like it did before. The flashing means it's flaked out and won't reset unless you turn off the car. There is definately something about the grounding of the MAP sensor that the Harlan RPM switch doesn't like.


Dave

 

What MAP switch do you have? Providing a ground to the Harlan really shouldn't (theoretically) do anything. The electricity will flow from the battery through the MAP switch and take the shortest path to ground (which definitely isn't through the Harlan).

If a 12v somehow made it back to the Harlan I would understand, but that just seems odd to me Dave.
-hype

 

1) 12VDC? Cigarette lighter
2) Relay? YES
3) RPM signal? COIL/TAM screw
4) YES: dash LEDs (see below)
5) No problems

LEDs (green=MEVI, blue=shiftlight)

 

So wire in a relay or no ??

 

you definately want to use a relay. I am assuming the turnon output on the Harlen switch is a transisterized output and not an internal relay. Usually an output such as this only provides 200-500 milliamps, where the solenoid probably needs about .5-1 amps. It may work if you do not use a relay but useing one will make your switch much more reliable, and eliminates the possibility of burning out the turnon circuit on the Harlen switch. This is how I will install mine if it ever arrives.

 

Now I need to reconsider everything now on my wireing plan.

Where does the relay go ?? inbetween what ??

-matt

 

check it my brotha.
http://www.vanillaice.com/webmasters...c/diagram3.jpg

 

links not workin

-matt

 

Works now.... I don't know what happened to my server
-hype

 

The relays introduced a ton more problems for me and a handful of other people like Nealoc and KevenSE. With the relay, I'd be lucky to get 3-4 VI engagements before it would flake out again.


Dave

 

You all probably bought a Relay that was defective, or not enough amps. Most people who have the relay have 0 problems.

I dunno - I know 0 about electrical stuff, except for + and - .

But that would explain it.

 

Nope, I had 3 relays on hand when I did the install and they all screwed up. The relays were the correct spec too. I'm not too worried now because I can manually override the VI when needed at the track. It's pretty sweet to hit the switch in 2nd and just leave it wide open when I enter 3rd at 5200rpms.


Dave

 

Whats the problem then with the setup that people have ?? Im wireing mine in a few days... what do to

-Matt

 

Good news. Having the manual switch is definately making life easier. Today, I wrapped out 1st and 2nd then let off. I looked down and noticed the Harlan flaked out right after I let off in 2nd. I flipped the manual switch on then off and the Harlan reset then continued to work. Before, I had to turn the car off completely to get the Harlan to reset.


Dave

 

Wouldn't you guys be better of just using a differnt brand of RPM switch? Perhaps the MSD? I know it cost more but it seems it would save you guys a lot of headaches and it is a small amount compared to what you have already spent on the VI setup. I would be very nervous using a Harlan switch with nitrous knowing it could fail .

 

My switches haven't ever failed, not once. Besides if it does fail the nitrous just doesn't activate. No biggie.
-hype