How to read rpm's with multimeter

[juntjoo]

I believe I've located the terminal in the firewall, if is the connector with a single terminal connected to only a cap, but my multimeter manual doesn't explain how to use the rpm function it has. Can anyone help?

 

[juntjoo]

No one has used a multimeter on their DSM to read rpm's?

 

[Arthris]

Thats not what ## looking for. On ## intake where the throttle cable bolts up there is a noise capacitor. The plug has two wires on it. That goes right to the Tach. I know that the signal is 12V. If ## DVOM can read a DC frequancy you might be able to read the RPMS that way

 

[juntjoo]

What's "dvom" ? Is this it ? The two in the back behind the bolt?

You must be logged in to view this image or video.

 

[Arthris]

A DVOM is a Digital Volt Ohm Meter. Look down by the Vacume line that runs from the intake to the Brake booster. Itll be there bolted to the manifold

 

[juntjoo]

Ah, you're saying on the intake. Are you sure? Haynes says its on the firewall. Remember I have an N/T. I'll have to check in the morning. Thanks

 

[DSM1G90]

What's wrong with the tach in the dash? Busted?

 

[juntjoo]

My tachometer is fine. I'm adjusting idle speed at the ISC. Look at this...

You must be logged in to view this image or video.

anyone familiar with what is going on in this picture? This is where I'm stuck.

 

[NHerron]

I have never heard of adjusting idle speed that way. Can you take a picture of the Haynes showing what it wants you to do

I believe the tachometer gets it's signal from the Ignition Power Transistor. As Chris was kinda sayin it's on the intake manifold if stock
http://www.mirage-performance.com/sonata/Ignition/Transistor001.jpg

 

[steve]

It's been awhile but the connector on the firewall for measuring RPM is a spade connector and reads half the actual RPM since it's only outputs half of the ignition pulses. (It's only connected to one of the signals from the power transistor to the coil)

The wire running to the A-59 Engine Speed Adjustment Connector is White/Black stripe.

Lets' see your multimeter that displays RPM. It needs to have a 2 cylinder setting.

Before you start adjusting the BISS, make sure that the throttle body still have it's ground strap, that the green wire to the Idle Position Switch (IPS) is connected and not broken, that the voltage on that wire goes from 0v when the throttle is closed to >= 5v when you open the throttle slightly. (Ignition on, engine stopped, wire connected to IPS)

Have you measured each of the coils in the ISC? DSM ISC motor testing & Replacement - YouTube
Have you taken the ISC out and cleaned it?
Does it move in and out when you turn the Ignition on? DSM ISC - YouTube
Do you still have the coolant lines connected to the FIAV?

In addition to finding the Engine Speed Adjustment Connector you have to ground two pins before adjusting the BISS. The Ignition Timing Adjustment Connector (A-60), same one you ground for setting the CAS and the ECU DLC mode pin (#10). BISS

Make sure the car is fully warmed up so that the FIAV is closed before adjusting the BISS.

 

[juntjoo]

Nherron, here's Haynes instructions:

You must be logged in to view this image or video.

which refer me to:

You must be logged in to view this image or video.

thanks for all the info. My multimeter does have a 2 cylinder setting, and 4 and 6. The resistance checked out fine on the ISC but I still have yet to apply voltage to it as Haynes instructed, or take it out and clean it. So I have a list to go through here. Btw, why do we ground the circuit for the BISS?

 

[steve]

Don't bother with the voltage tests in the manuals. It won't tell as much as watching it like in the second vid.

Why ground the circuits? Because that's how you tell the ECU that your adjusting the BISS so it will position the ISC in the correct spot for adjusting the BISS.

 

[juntjoo]

Don't bother with the voltage tests in the manuals. It won't tell as much as watching it like in the second vid.

Why ground the circuits? Because that's how you tell the ECU that your adjusting the BISS so it will position the ISC in the correct spot for adjusting the BISS.

Ah, thanks. I figured it was something like that.

 

[steve]

I see that the Haynes manual in steps 33 and 34 tell you what to ground by not why.

But why would you have to do 36e, the ISC must not be disconnected during the adjustment.

 

[pauleyman]

Throw the haynes manual in the trash. OEM manual is too cheap to be without anymore. Even when they were 100$ they were still a bargain. You do not need to hook up an aftermarket or diagnostic tach to set idle. Just use your dash or a datalogger.