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aftermarket speedo troubleshoot

 
  #16  
Old 05-16-2019, 03:09 PM
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Originally Posted by GoldCo View Post
OK, so I think I may have my speedo wired incorrectly — currently I have the two "speed sensor signal" wires from the speedo wired to LG/BK (5) and PK/O (2). I don't recall why I did it that way, but I'm guessing that instead of PK/O it should be R/PK (i.e. both leads coming from VSS). Then I could simply program the speedo PPM for the raw 75,600 value, right? I think in my head I was thinking that I had to somehow get the post-PSOM signal to the speedo, which I don't believe is the case anymore, correct?
If you have the 1st speedo in the PDF file
This page tells how to hook it up:

.Speedometer4-Pin Connector:
•Terminal A – Red w White Tracer Wire= Voltage Supply to Digital Sensor
•Terminal B – Tan w Wht Tracer Wire= Speed Sensor Signal *
•Terminal C – Brown w Blk Tracer Wire= Speed Sensor Signal **
•Terminal D – Green Wire= Dash Lights
When a 2 wire analog sensor is used, connect both wire to terminals B and C. In most cases the polarity is not a concern. If the speedometer is not receiving a signal the installer should try switching the wires.

When a 3 wire digital sensor is used, connect terminal A to the voltage supply for the sender, connect terminal C to the sensor negative/ground wire and to a negative/ground potential and connect terminal B to the sensor signal wire"

What I read, you will hook the PSOM output pin 7 LG/BL wire to Terminal B
Hook Terminal C to ground. It will be like the 3 wire digital setup but without the power hooked up as the PSOM has its own supply(I hope)
Then manual program for 8000 pulse per mile(or drive the measured mile). The sensitivity setting I would leave it alone till you get it working and see how it responds.

The PSOM speed output is a AC voltage output in reference to ground

Here is my project: https://www.ford-trucks.com/forums/1...r-display.html
 
  #17  
Old 05-16-2019, 05:07 PM
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Smile Thanks for reply

So wondering why you suggest that? Isn't my VSS a 2-wire setup? I can certainly give what you suggest a try, but I wouldn't have thought to do so based on the directions…

Originally Posted by Eddiec1564 View Post
What I read, you will hook the PSOM output pin 7 LG/BL wire to Terminal B
Hook Terminal C to ground. It will be like the 3 wire digital setup but without the power hooked up as the PSOM has its own supply(I hope)
Then manual program for 8000 pulse per mile(or drive the measured mile). The sensitivity setting I would leave it alone till you get it working and see how it responds.

The PSOM speed output is a AC voltage output in reference to ground

Here is my project: https://www.ford-trucks.com/forums/1...r-display.html
 
  #18  
Old 05-16-2019, 06:26 PM
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Originally Posted by GoldCo View Post
So wondering why you suggest that? Isn't my VSS a 2-wire setup? I can certainly give what you suggest a try, but I wouldn't have thought to do so based on the directions…
Are you using the PSOM at all?


If not, then hook the VSS to those B and C terminals directly. Then the best way is to do the measured mile for calibration. If it don't work still then time to call the company up....
 
  #19  
Old 05-16-2019, 08:02 PM
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Yes, I’m using PSOM to control E4OD and make PCM happy. (Using the OEM harness(es) from the ‘95 donor.)

But I was wondering if I spliced speedo in to VSS directly, as you suggest, before PSOM…

Any disadvantage?

Originally Posted by Eddiec1564 View Post
Are you using the PSOM at all?


If not, then hook the VSS to those B and C terminals directly. Then the best way is to do the measured mile for calibration. If it don't work still then time to call the company up....
 
  #20  
Old 05-17-2019, 07:14 AM
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Originally Posted by GoldCo View Post
Isn't my VSS a 2-wire setup?
Yes it is. The Red/Pink (523) and Light Green Black (519) wires are the VSS signal. Those are the input to the PSOM.

The way you described before how you had that speedometer hooked up will not work. Either use the raw VSS signal wires or use the signal output and related ground from the PSOM. You cannot grab one side of the raw VSS signal and ground.
 
  #21  
Old 05-17-2019, 05:45 PM
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Originally Posted by GoldCo View Post
Yes, I’m using PSOM to control E4OD and make PCM happy. (Using the OEM harness(es) from the ‘95 donor.)

But I was wondering if I spliced speedo in to VSS directly, as you suggest, before PSOM…

Any disadvantage?
Ok, I see what you are doing now.

What you do is on Terminal B – Tan w Wht Tracer Wire= Speed Sensor Signal * hook that to the R/PK wire from the VSS
Terminal C – Brown w Blk Tracer Wire= Speed Sensor Signal ** hook that to the LG/BK wire from the VSS

Then drive a measured mile to setup the aftermarket speedo. Or if you know how many teeth are on the VSS tone wheel in the axle and tire circumference you can figure out the pulse per mile that way.

Doing it that way gives you much more play in how to setup the speedo, The PSOM you can change the tire ratio only 6 times before you cannot change it again(unless you reprogram EEPROM back to 6)
 
  #22  
Old 05-17-2019, 08:02 PM
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Wish me luck.

Ok, so sounds like 2 votes for what I postulated in post #7 above…

I’ll go try it after dinner. Thx
 
  #23  
Old 05-17-2019, 10:29 PM
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Gah!
No dice.

Though, I'm wondering if I might've broken a wire when I was removing the previous splice (using those plastic splice clamps that cut into both wires) — in addition to the speedo still not working, now the tranny is shifting late and hard.

Too tired to deal with it tonight. Was really hoping this would work and I could check this off the list and move on to the next issue!
 
  #24  
Old 05-22-2019, 11:19 PM
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well [email protected] still no luck. cut out the splices and replaced using wire nuts. programmed speedo using the pulse/mile method and still nuthin'. just to make sure i even switched the two wires in case polarity was an issue, and that didn't work either.

guess i'll try bill's suggestion one more time using the wire nuts before calling speedway. so frustrating not knowing whether the gauge is defective or the problem lies elsewhere...

 
  #25  
Old 05-23-2019, 07:25 AM
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You say you are using the PSOM for the E4OD also. Are you using the PCM also for this?
You could also use an extra PSOM with its input signal in parallel with the other PSOM to isolate it. The second PSOM output signal may also boost the VSS output signal by setting its Calibration conversion constant to 1.0.

When a PSOM is used with a transmission mounted VSS the Calibration conversion constant is set to 1.0.
The PSOM will not change the input signal and its output frequency will be the same as its input frequency when its Calibration conversion constant to 1.0.
 
  #26  
Old 05-23-2019, 06:11 PM
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Exclamation

From what I understand, the E4OD (being electronically-controlled transmission) gets info from the PCM on shift points, based on the PSOM interpretation of VSS. So that is all I meant — my VSS is the standard axle-mount unit on this '88 Sterling 10.25 (not in tranny).

I'm using heavily pared-down OEM harness(es) and PCM with this 5.8 and E4OD (1995). I've got a PSOM circuit board stashed behind the dash and then the aftermarket Omega gauges. This is all in a 1952 F3.

I'm going to go back and try your earlier suggestion to grab the post-PSOM signal instead of the raw VSS signal. If that doesn't work, I can only assume I have a bad speedo from Speedway (which, unfortunately, wouldn't surprise me after a defective tach, and two bad master cylinders from them; at least they've replaced the stuff, thus far).

Hoping to get this figured out so I can move on to why my gas gauge doesn't work.

Originally Posted by subford View Post
You say you are using the PSOM for the E4OD also. Are you using the PCM also for this?
You could also use an extra PSOM with its input signal in parallel with the other PSOM to isolate it. The second PSOM output signal may also boost the VSS output signal by setting its Calibration conversion constant to 1.0.

When a PSOM is used with a transmission mounted VSS the Calibration conversion constant is set to 1.0.
The PSOM will not change the input signal and its output frequency will be the same as its input frequency when its Calibration conversion constant to 1.0.
 

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