Electrical ;TPS, PCM and OD Trans Control

trailbound · 01-07-2009, 12:04 AM

So I'm doing a 12v swap into a 77 1/2 ton ford.

I've already found the DIY for TPS delete and using a voltage regulator to control the Alt.

I cant seem to find a wiring diagram for a 92 w250.

By removing the PCM I will have to run the 2 DIY's mentioned above, but i do not know which of the 3 wires on the TPS is 12v, and which wire on the OD is 12v?

Philip · 01-07-2009, 01:15 AM

A 518/46RH trans only has a two wire plug for the OD. Power to one wire and ground the other. Its just a controll solenoid. It doesn't care which wire is hot or ground.

If your not using the PCM on your swap the TPS is not needed. That sensor feeds a signal to the PCM. The trans itself has no use for that signal.

To control OD just pickup a Hobbs adjustable pressure switch. Plumb it into the test port for the governer on the trans. Then adjust it to the MPH you want OD to come in at. The down side to this way of hooking it up is it will only go into OD at the set MPH. There will be no part throttle upshift. It will work if the main thing. Any time you would drop below the set point it would down shift to 3rd.

__________________
93 W350 w/duals, fuel pin turned, 6X.018" injectors, 4" exhaust, 3" air intake horn, Super HX40/16, auto, 3:07's axles, 2" skyjacker lift, B&W flatbed

trailbound · 01-07-2009, 01:43 PM

ok, so by taking out the PCM, i don't need to do a pot. and i can just take the TPS off. But the TPS has the ability to semi adjust shift points.

How will the trans react without a TPS and without a pot?

Philip · 01-07-2009, 02:11 PM

Quote:

But the TPS has the ability to semi adjust shift points.

The PCM controls the OD shift. Without a PCM there is no need for the TPS. The solenoid inside the trans is a on/off electric solenoid. The TPS is nothing but a variable voltage signal for the PCM.

All the trans sees from the PCM is one of the wires going to ground to engage the soleniod. The trans has no idea it is controlled by a PCM. All it wants is a ground signal on one wire from the solenoid to engage OD. What controlls the ground doesn't matter. It could be a PCM or a single toggle switch or a Hobb's switch.

__________________
93 W350 w/duals, fuel pin turned, 6X.018" injectors, 4" exhaust, 3" air intake horn, Super HX40/16, auto, 3:07's axles, 2" skyjacker lift, B&W flatbed

01-07-2009, 12:04 AM	#1 (permalink)
trailbound Cummins Fan Join Date: Dec 2008 Location: stockton ca Posts: 34 Thanks: 0 Thanked 0 Times in 0 Posts trailbound's Truck Pics	Electrical ;TPS, PCM and OD Trans Control So I'm doing a 12v swap into a 77 1/2 ton ford. I've already found the DIY for TPS delete and using a voltage regulator to control the Alt. I cant seem to find a wiring diagram for a 92 w250. By removing the PCM I will have to run the 2 DIY's mentioned above, but i do not know which of the 3 wires on the TPS is 12v, and which wire on the OD is 12v?

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01-07-2009, 01:15 AM	#2 (permalink)
Philip 1ST GEN MODERATOR Join Date: Nov 2007 Location: Indiana Posts: 5,104 Thanks: 2 Thanked 130 Times in 120 Posts Philip's Truck Pics	A 518/46RH trans only has a two wire plug for the OD. Power to one wire and ground the other. Its just a controll solenoid. It doesn't care which wire is hot or ground. If your not using the PCM on your swap the TPS is not needed. That sensor feeds a signal to the PCM. The trans itself has no use for that signal. To control OD just pickup a Hobbs adjustable pressure switch. Plumb it into the test port for the governer on the trans. Then adjust it to the MPH you want OD to come in at. The down side to this way of hooking it up is it will only go into OD at the set MPH. There will be no part throttle upshift. It will work if the main thing. Any time you would drop below the set point it would down shift to 3rd. __________________ 93 W350 w/duals, fuel pin turned, 6X.018" injectors, 4" exhaust, 3" air intake horn, Super HX40/16, auto, 3:07's axles, 2" skyjacker lift, B&W flatbed

01-07-2009, 01:43 PM	#3 (permalink)
trailbound Cummins Fan Join Date: Dec 2008 Location: stockton ca Posts: 34 Thanks: 0 Thanked 0 Times in 0 Posts trailbound's Truck Pics	ok, so by taking out the PCM, i don't need to do a pot. and i can just take the TPS off. But the TPS has the ability to semi adjust shift points. How will the trans react without a TPS and without a pot?