Tach question

[Diesel_brad]

What exactly does the tach use for a signal? Does anyone run an aftermarket tach? How/ what kind of signal did you use. And what model number tach did you use

 

[13fcolt]

keeping an eye on this one. i still have not replaced the tach i broke.

 

[CDX825]

The factory tachs use a hall-effect type sender. So if you wanted you could use an aftermarket gauge. There are quite a few tachs that will work with hall-effect senders.

 

[GenLightening]

It basically counts the teeth on the IP gear with a magnetic sensor and the pulse that's generated makes the needle move. There are some aftermarket units that run off a magnet that's gets attached to the crank or alternator pulley. Those don't usually work as well.

 

[Diesel_brad]

My reason for asking, is that when i swap over to my powerstroke, i want to keep my stock 86 tach but dont think the powerstroke uses the same signal

 

[OLDBULL8]

My reason for asking, is that when i swap over to my powerstroke, i want to keep my stock 86 tach but dont think the powerstroke uses the same signal

The PSD's use a VSS mounted in the rear pumpkin, triggered by a tone ring, that signal is fed to the PCM.

 

[LCAM-01XA]

That's for the speedometer tho... or do you mean the PSOM calculates the engine speed based on axle speed and gear currently used in the trans? Then how does it work with a stick-shift trans, the PCM or the PSOM have no knowledge of which gear you're in then, so the VSS signal cannot be used to determine engine speed.

 

[trackspeeder]

Tach signal for the PSD comes from the CPS. Goes to the PCM then to the tach.

 

[LCAM-01XA]

And the CPS is the $60-something part that every 7.3 PSD owner should keep a spare of in their glove box?

 

[dyoung14]

Pretty sure it wont work, so you will either have to buy aftermarket, or swap a newer dash and all that junk in

 

[LCAM-01XA]

the gauge cluster of the PSD trucks is driven by the PSOM, so maybe it's possible to retrofit a tach off a newer truck with a PSOM to drive it? I know the PSOM retrofit alone is possible cause someone on TDS did it in his van cause his replacement E4OD was of the newer type without a VSS cable so he needed the axle VSS signal to be translated for the PCM to understand it...

 

[trackspeeder]

And the CPS is the $60-something part that every 7.3 PSD owner should keep a spare of in their glove box?

$20 buck for the POS Ford gray unit. Mine is still in the glove box.

Think I just jinxed my self.