Car Stereos: remote start tach wire 2004 escape, digital multimeter, remote starters

Question
QUESTION: I am trying to locate a good source for the tach wire on my remote start. the motor has coils at each cylinder & I can't determine which wire to use. the injectors are under the manifold, not easily accessible, not sure where to start behind the gage cluster. Is it really needed since today's cars are pretty good about self monitoring. the remote start works fine without it. thanks

ANSWER: Hi Drew,

I know what you mean about the inaccessible injector wiring.  I usually install Directed remote starters, and they don't usually work very well with coil wires in Ford vehicles, so I almost always try going to an injector.  

One solution is to find the injector wires at the PCM, which is mounted into the firewall.  If I recall correctly in the Escape, it's either at the top of the firewall, in the center behind the engine; or near the top of the firewall on the passenger side.  Each of the injectors' wires run to the PCM, and are much more accessible there.  Unfortunately, I don't have the injector wire colors available; usually I look for a tan or tan/black.  If you can get a glimpse of an injector harness under the manifold, that should help you.

To test for a tach wire, use a digital multimeter with an AC voltage function.  The correct wire should show no volts with the engine off, but will show AC voltage with the engine running.  Depending on the type of wire, the voltage reading may be anywhere from 1 volt to 8 volts.  Often it will increase as you rev the engine, but not always.  If your suspect wire doesn't show AC voltage with the engine running, then don't use it for your tach connection.

I always prefer a tachometer connection, because it's the most reliable for a remote starter; but a good voltage sense system will work perfectly well in most cases.  If your remote start unit is working without the tach connection, isn't grinding the starter, and starts in all weather conditions, then you probably don't need to worry about the tach.  My experience with some voltage sense systems is that you often need to adjust the crank time when cold weather hits.   Another advantage of a tach connection is that it's the only monitoring type that will give you over-rev shutdown; voltage sense systems can't tell when the engine is being revved.  

Hope this helps!

Brian

---------- FOLLOW-UP ----------

QUESTION: would you test for the tach wire like the injector wire?

Answer
Hi Drew,

I'm not sure I understand your follow-up question.  In just about any Ford vehicle, an injector wire is the only type if wire I'd use for a tach sense connection.  However, some brands of remote starters might work better with coil wires than the ones I install; and I do commonly use coil wires or other types of tach wires in many other vehicles.  In any case, the testing procedure is the same for any wire I'm hoping to use as a tach connection:  test for AC voltage when the engine is running.  You'd test the same way whether you were using an injector wire, a coil wire, or testing wires behind the instrument cluster.

Hope this helps!

Brian