Hey all I don't ever post here, but since I drive a 1999 my ECU is closer to a 5th gen than a '98. I got a Harlan Rpm Switch for my MEVI, but I can't get it to work by tapping into my ECU for some reason. The tach wiring on my car matches the 5th gen ECU (green/white wire), but for some reason when I ground the Harlan the tach signal drops to 0. Has anyone had problems with Harlan products, or does anyone even have a shift light
Here's a couple of other threads that describe my situation
Does anyone with a '99 have a Harlan Shift Light?
Shift light install; Of course the '99s are different
Which ECU pin is pin 1?
-hype

 

I have the shift light. Mine works pretty much the way it's supposed to. Hook up black to ground, red to switched +12V, green to tach signal line at back of gauges. Before you make any other connections, make sure at least these three are hooked up and your tach is still working properly. If it's not, then you either have a defective unit or maybe your signal line is shorting out. Beyond that, I'm not sure I can be much help. Good luck.

 

Ants97SE has the Harlan shift light installed on his 97....talk to him! :P

 

Russ the ECU wiring on my car is like that of a 5th gen hence my post here :P The 95/96 and I think even the 97s have a screw that says TAM that they can tap into. My wire is the same color as the 5th gens, so I was curious to see if any 5th gens have had my problem.
On the Harlan when I connect the 12v the tach is fine. When I connect the 12v and tach line everything is fine. Only when I ground the Harlan does the tach signal die. As long as the Harlan is grounded and the tach signal is connected the tach signal dies.
I guess my next option is to try wiring to the coil instead of the ECU and send another email to Harlan.
-hype

 

If you hook up the ground first (leave tach disconnected) then apply +12V to red, does the LED light up for 2 seconds? Assuming the rpm switch and the shift light are based on the same module, it should also have the same "self-test" feature. If it doesn't you may in fact have a bad module.

BTW, the Harlan website seems to be down. Do you know if this guy is still in business? A friend of mine wanted to get a shiftlight too.

 

Hey Sly I tested my Harlan tonight and the light does light up when the unit is first powered up. I still don't know why when I connect the tach signal the unit kills my tach Tomorrow I'm going to try to wire the Harlan up to my coil and see if that will work.
On your shift light that's tapped into the ECU (green/white) what settings did you use? Right now my Harlan is set to 6 cylinders and 2000 rpms (for testing). Should I be setting the cylinders to something else (for the Fbodies Harlan says to use 4 cylinder mode)?
I reallly need to get this working so I can install my MEVI in a few weeks.
Thanks for your help.
-hype

 

Hey man...I put one on my 5th gen as well. I used the 6cyl mode as well. There are TWO green white wires...One is kinda a reverse of the other (you need the WHITE jacket with the green stripe). Make sure you have tapped the correct one. On the 5th gen if you pop the console out and "face down" its on the left plug. The wire is to the left of the GREEN jacket with a white stripe and to the RIGHT of a RED wire (again 5th gen)

Reference ICE's site for pics. Plug Wire location Picture

Let us know if you should have anymore trouble. Also when you loose the tach, does the Harlan light up when its supposed to?

 

Interesting. I tapped that wire, and to make sure I got the right one I even tapped directly from the ECU (it was the same wire). Both times when the Harlan was grounded the tach signal was disrupted, but the shift light does work When I only connect the 12v and ground the Harlan lights up like it's supposed to.
Out of all the people I've talked to no one can figure out what would cause the tach to die. The Harlan is wired in parallel, so one would think the tach wouldn't be affected.
Thanks for your help guys
-hype

 

OK, this is the last thing I can think of...check the resistance between the signal wire and ground of the module, it should be very high. If the unit is providing no resistance between sense and ground then it's shorting out the tach signal.

I'd be hesitant to hook it up to the Coil trigger wire, it might cause a misfire if it's shorting the signal.

BTW, mine is set to 6 cyl mode at 6K RPM.

 

Hmmm. I would check on that resistance idea for sure. Second...does the wiring colors match that on the pic of the 2000+ on ICE's website?
I have access to a FSM should we need to go that far but not sure if a 2001 FSM will be of any use to a 99 user...?

Where are you grounding it to? Should not matter but I am curious.

 

Ok I just checked the resistance and it was 4.3 MOhms, so that's quite a bit. I am somewhat hesitant to hook the Harlan up to the coil, but I will pull it immediately if I hear any problems. It's also my last resort since the ECU doesn't like the Harlan for some reason.
When I tapped the ECU I did tap that exact green/white wire, and it's the only one there as far as I can see. It should also be the correct wire because the Harlan gets the tach signal from it and it shorts the tach when the Harlan is connected. I get the same symptom whether I attach the Harlan to the wire behind the cluster or at the ECU at pin 5 (I did both). Right now I ground the ground to the metal below the shifter paneling, but I also grounded to other places to make sure it wasn't the ground (not that it should matter).
I'm running out of ideas
-hype

 

Here is another idea, althought the SL should not be creating or draining really any resistance, have you checked the resistance upstream (between SL tap and tach) while connecting the various pieces of the SL? Like test one with nothing but the green wire connected, then one with the positive, one with the negative, then one with all three. This is done with ignition off. Then repeat with ignition on.

I am thinking that even though we are pretty sure we are creating a "short" I would like to know when for sure it shows up. Does it make sense or am I grabbing for a life preserver?

 

Makes sense to me, and besides we're getting down to the wire so anything might help. I have to run to the store to get some parts to move my sub because I just installed my modified RSTB (it didn't fit :P ), but I'll definitely test that out. If that doesn't tell us anything I'll try tapping the coil and just hope that it works.
Thanks a lot for the support and ideas
-hype

 

Best O luck to ya! Keep us posted...

 

Ok here's the deal. I kinda knew this from playing with this so much, but I tested everything again to make sure. I can connect the 12v and tach lines all day long in any location and everything is fine. With the ignition on or off doesn't make a difference (obviously the tach doesn't work with the ignition off). The ONLY time the tach drops to 0 is when the ground and the tach signal are attached together. It doesn't matter if the 12v is connected or not; when the ground and tach are hooked up to the Harlan the tach no longer works
I guess it's on to the coils.
-hype

 

Update: I went into the engine bay and tapped the coil wire. For some reason my Harlan will run when running off the coil, but won't when wired off the ECU I was afraid it might kill the coil signal, but the ECU never went off so I guess the coil is still firing. Do you know what exactly would happen if the coil wasn't firing? I'm assuming it would be like a dead cylinder and the car would run rough, but I want to make sure before I wire everything up for good.
At least I finally got it working
Thanks again
-hype

 

Very strange that it will work with the coil signal but not the tach. Anyway, glad to see it's working now. Let's hope it stays that way when you finish with your MEVI project.

 

It should be okay tapped off the coil. If the coil dies, the car will run rough, so it would be noticeable immediatly. A lot of people run the MSD window switch for nitrous activation off the coil wire...