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mspiegle
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Joined: Wed Mar 19, 2025 8:25 am
Location: Los Angeles, CA

Enabling 12v PWM Tachometer Output

Post by mspiegle » Sat Mar 29, 2025 6:10 pm

I have an ‘09 Rossion Q1 which uses a Ford Duratec 3.0L V6 and EEC-V (MPC-161, DOAV7). The engine and PCM are likely based on an ‘04 Ford Escape V6, but heavily modified for the Rossion Q1.

I tried to clone the Q1 PCM to a Ford Escape unit from eBay, but the cloned PCM wasn’t driving the Q1’s analog-style tach (12v PWM) from pin #48 like the original. A factory Ford Escape drives the instrument cluster via SCP BUS (pins #15 and 16), so this wasn’t too surprising, but why didn’t it work after reading/writing the entire BIN? I initially thought this was a software problem, but helpful conversations with Cory from Derby Wiring Solutions, 86GT, and sailorbob, guided me to look for the answer in hardware. Once I got out my magnifying glass, the answer was obvious. The Q1 PCM had additional circuitry to connect a tach signal from the ignition chip to pin #48.

Once the SMT components were added to the eBay PCM, the tach output “just worked”. It continued to work even after reverting the cloned PCM’s BIN to the factory Ford Escape code, so this mod may not require any help from software. My ignition chip is labeled “V6 COP/SPI SA”, but I suspect it would work on any PCM with a supporting chip and PCB layout so you could use the newer COP PCMs on older cars.

Here’s what you’ll need to do the modification:
  • 1x Resistor, 10k, size 0603, CRCW060310K0FKEA
  • 1x Resistor, 7.5k, size 0603, CRCW06037K50FKEA
  • 2x Resistor, 1.2k, size 1210, RK73H2ETTD1201F
  • 2x Resistor, 2.2k, size 1210, CRCW12102K20FKEA
  • 1x Transistor, NPN Single BJT, size SOT-23, SBC847CLT1G
I’m no hardware expert, so some of you may know of better components to be used. In any case, here’s a couple images showing where these components were installed:

Top_Side_EEC-V.jpg
Bottom_Side_EEC-V.jpg

I hope this is encouraging to others who are interested in a similar modification. I don’t have experience with any other EEC-V, but feel free to reach out if you think I can help you.
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2009 Rossion Q1
IG: d4rq1

DWS
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Joined: Wed Apr 02, 2025 3:05 am

Re: Enabling 12v PWM Tachometer Output

Post by DWS » Wed Apr 02, 2025 3:23 am

I don't have pics, but I've also confirmed this works on a MLC-411 crown vic computer so in theory might be able to swap a gauge cluster over from a mustang to have a tach or use the pin for an aftermarket tach.

I tested a bunch of EEC-V computers (all 4 bank), and the ignition control chip mentioned above seems to always generate a 5v square wave tach signal on every one of them. The v10 computers (even if it's for a v8) has a really weird pattern where it's 5 pulses, a break then 5 pulses. Besides that it's just a simple 50% duty cycle PWM style tach signal that as rpm increases the frequency increases.

5v signal from ignition control chip for effectively everything except the v10 computer.
Image

Here's the tach output for a v8 computer that's the same hwid as a v10 computer (the v10 computer looks the same).
Image
Ford EEC-V Tuner Site
  • Immo Off, PATS, Security only currently
  • Bank Swapping
  • View VIN and other info about the bin file
PHF to BIN Converter/Viewer

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