Aftermarket Tach install

I bought an aftermarket tach...and I need to know which wire to splice on my coils. I have 2 coils...and a total of 8 wires...which one do i splice?

I found which one it was... black with a yellow stripe on the coil.

[kokopelli]

..........are you sure ? What kind of tach did you buy ?

yeah, works good. They share the same negative and the black wire with yellow stripe is it. I bought it at O'reillys for 30 bucks. I dont remember the name brand. I found the wire in the service manual and it works well.

[kokopelli]

crazyhorse3030 , The reason that I asked is that there have been many that have had trouble wiring or asking questions about wiring an aftermarket tach .

I installed a Sun Pro Super Tach II in my Taco and had worked extensively with the Accutron tech support center . According to them , you cannot wire off the coil packs and get an accurate reading without a tach adapter .

I'm not saying that you're wrong ! What I am saying is that if you indeed did find a way to wire off the coil ....it's sure a HELL of a lot easier than the way I had to do it . What cylinder number did you set on the tach itself ? Curious !

I'm writing your directions in the back of my service manual for future reference .

Thanks for sharing this ,it could be a lifesaver for someone .

Also ....where did you wire the lighting to ?

Well, I am not quite sure if my wiring method makes the tach measure exactly right. I assume that is it measuring the engine RPMS right. I went to Autozone and found a wiring diagram in the back of a service manual...and noticed that each coil pack shared the same hot wire, and each coil pack shared the same negative wire. (*I am working with a 2.7 liter 4 banger here in case ur working with a 6 cylinder). From each coil there was a ground...which is your brown wire. That leaves 1 wire left per coil pack. Those each go to fire the motor.

I wired up to the coil pack closest to the front of the truck. If you can let me know if I done it wrong , just let me know...I am open to advice when I make mistakes.

Also, I just wired the lighting to the ignition fuse. I couldnt find the light switch wire, so it lights up everytime I turn it on.

...And my tach is set on 4 cylinder.

Once again, if I am wrong...PLEASE LET ME KNOW! As far as I know it works.

I drive a 1998 Tacoma 2.7 Liter 4x4. Now according to the tach, the motor idles approxmiatly 800-1000 rpms. And 5th gear at 55mph at about 2,000 RPMS.

[img]/ubbthreads/images/graemlins/beach.gif[/img]

[kokopelli]

crazyhorse3030 < [img]/ubbthreads/images/graemlins/goodpost.gif[/img] Hey ! That's really cool! Your idle and 55 MPH ....RPM's sound right on the money too . I'd say that you nailed it ! [img]/ubbthreads/images/graemlins/applause.gif[/img]

What I was told .....and it makes 1/2 sense is that if you went to the coil packs is that you either needed a "Tach adapter " or a tach that is graduated into 2 cylinder setting , which makes the other 1/2 sense if you only hook to "one" of the coil packs . Logically , I figured there had to be another way .

I chose to keep all my wiring inside the passenger compartment and went to Pin 15 on the ECU , which is a black wire , which was the way Acutron reccomended . As far as the Tach lighting , because the dimmer works on the ground side ; it causes the lighting on the tach to works backwards from the dash .

I never meant to suggest you did anything wrong , it was my dry sense of humor showing through ; In my waay I'm congratulating you for solving a puzzle that I nor the techicians from the manufacturer couldn't .

The problem I encountered was that the scematics are supposed to be viewed from the engine compartment and NOT from the interior....once I figured that out it was a piece of cake !.......but nobody could tell me that either . [img]/ubbthreads/images/graemlins/violin.gif[/img]

Being the Chicken S**T I can be sometimes .....I was extremely cautios hooking up to the ECU...... ! I also found the factory tach hook up wire on the speedo cluster . [img]/ubbthreads/images/graemlins/spank.gif[/img]

Did you fuse any of your connections ? They reccomended a 3 Amp fuse in the siginal wire to protect the ECU . I'm using a 1 Amp and haven't blown it yet . I continued to fuse all the other conections also .

What you say does sound logical...one coil pack = 2 cylinders. And I only have it wired to one coil...so I can't give a reasonable answer on why mine seems to work. When it is idling and I kick on the A/C, the needle hops up to around 1100 RPMS...Does that sound right to you? I wish I could find someone with a tach that came out from the factory and compare them.

But everything seems to work correctly. And no mine isnt fused...I prolly should do that though. And the reason I hooked my lighting to the igntion is because I was too lazy to figure out how to hook it ot the light control.

[kokopelli]

crazyhorse3030 < The jump in RPM that you experience when turning the air on is an intentional increase in idle speed to keep the engine from stalling at an idle because of the extra power needed to run the A/C compressor . Your RPM figures are identical to mine .... which have been verified with others in here that do have factory tachs . The rear end gearring between trucks could affect those numbers also .

See my set-up :
http://www.cardomain.com/memberpage/652817

Here is a pic of my truck. This is before I put on the KC offroad lights on the brushguard and before I put in the tach.

http://www.cardomain.com/memberpage/828481