Tach and RPM?

Home / the12volt's Install Bay / Car Security and Convenience / Tach and RPM? (

Topic Closed)

Welcome Guest :)

Members

< Prev Page Next Page > < Prev Topic Next Topic >

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: November 17, 2005 at 1:48 AM / IP Logged

This is a comprehensive list

If it's not listed, I'm sure the guys on this site have seen it before and could give you the info on what you're looking for.

equate

Copper - Posts: 118

Joined: March 07, 2005

Posted: November 17, 2005 at 10:31 AM / IP Logged

I know this. I am helping my friend to get the tach wire on some special Asian version vehicles. For example, which is the tach wire of the following vehicles:

1. TOYOTA VIOS 1998

2. TOYOTA TERCEL 1997

3. BENZ E280 1996

Preyhunter

Member - Posts: 34

Joined: October 19, 2004

Location: United States

Posted: November 17, 2005 at 10:46 AM / IP Logged

2. TOYOTA TERCEL 1997

Tachometer BLACK/ blue AC check connector

note: The check connector (diagnostic) is located in the left rear corner of the engine compartment. The tach can also be found at the ignitor in the same locatio

Preyhunter

Member - Posts: 34

Joined: October 19, 2004

Location: United States

Posted: November 17, 2005 at 10:50 AM / IP Logged

Maybe someone else can answer this question...is the tach wire the ONLY wire coming off the coil that would show AC? If so, you could just put your DMM on the coil wires to see which one shows AC. I wouldn't recommend going this route at this time, because there may be other wires showing AC. I simply do not know.

cntrylvr79

Silver - Posts: 582

Joined: July 02, 2005

Location: United States

Posted: November 17, 2005 at 10:55 AM / IP Logged

When in doubt you can always get a tach source at an injector. If you look at the injectors you'll see that one wire will be the same color at all of them. With your meter set to ac voltage, simply probe the other wire and rev the engine a bit. You should get an ac reading that goes up as you rev the engine. Good luck hope this helps.

Cause I'm So white and nerdy...

First Class Certi-fried installer

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: November 17, 2005 at 11:02 AM / IP Logged

No listing for the Vios yet, but the other two are listed-

1997 Toyota Tercel Security Information

Tach BLACK/ Blue In Blue 12 Pin Connector in Passenger's Kick Panel

1996 Mercedes E-Class Security Information

Tach Black Coil

Frequency of the pulses would be dependent on the number of cylinders of the car, are you looking for specifics on that, or just want to find out where to tap into a suitable signal?

KPierson

Platinum - Posts: 3,527

This member consistently provides reliable information

Joined: April 14, 2005

Location: Ohio, United States

Posted: November 18, 2005 at 7:02 AM / IP Logged

That tach signal will vary widely from car to car. The wave shown in the 2nd link (slowly rising, quickly dropping off) appears to be a signal to drive a distributor. If you grab a signal off of a crank angle wire (or cam position) it will be a perfect square wave. Fuel injectors are typically quick spikes.

And, I know people will disagree with me on this one (someone somewhere always does), but tach wires are NOT AC signals. They are pulsing DC. Pulsing DC can be read (not accurately though) by using the AC function on a meter. This is because the tach signal has a frequency associated with it, and the AC function looks for a frequency. The voltage that makes up the tach signal comes from the DC car battery.

Kevin Pierson

dualsport

Silver - Posts: 983

Joined: September 27, 2005

Location: United States

Posted: November 18, 2005 at 9:04 AM / IP Logged

Yeah, pulsed DC is more like it than AC, since the polarity isn't really reversing, as it would with the AC in something like household line voltage.

That trace was to an ignition coil input; the output from the coil is thousands of volts, and goes to the distributor (unless it's a distributorless setup). That side you don't want to touch; that'll curl yer hair. Tach and RPM? - Page 2 -- posted image.

Might be safer to stick with the ign coil input or injector signals rather than tap into the crank angle sensor, unless the connection can be made properly and weatherproofed, because the lower level signals are going to be more sensitive to anything that might degrade the signal.

equate

Copper - Posts: 118

Joined: March 07, 2005

Posted: November 18, 2005 at 11:44 AM / IP Logged

Thanks for all above.

For TOYOTA TERCEL, I have a picture here. I don't really know what is compartment of the engine.

Tach and RPM? - Page 2 -- posted image.

Is it the black pen circel part that I can get the TACH wire?

pss5075104

Copper - Posts: 144

Joined: February 09, 2005

Location: United States

Posted: November 18, 2005 at 4:31 PM / IP Logged

i think it is always a hell of a lot easyer just to go to the injector.

MECP First Class Certified Installer.

Nothing is impossable, it's just more expensive.

< Prev Page Next Page >

Printable version

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

Search the12volt.com

Follow the12volt.com

Disclaimer: *All information on this site ( the12volt.com ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information.