5.0 Swap

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St33zyxSaleen

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Jun 25, 2017
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#1
I recently completed my 5.0 swap in my 98 V6. After topping the fluids and preparing for the engine break in I was created at cranking by a flashing pats light and silent fuel pump. The 94-95 mustang did not use pats. I know this for a fact because I’ve pulled up the key options at work.

I’m wondering does anyone have any experience in this swap the the 96-98 chassis. Everything under the hood has been swapped over and so has the ECU(PCM) it’s harness & the EEC & engine harness. The only thing I’m wondering is how do I eliminate or bypass the remaining pats systems in the car.
 

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#2
I'm no sn95 expert...but...seems like you may need the dash harness, too. PATS is a very hard system to get around.

If you got a schematic for the 95 computer you may be able to successfully bypass the PATS system. You're looking for grounds, cranking, and key on engine off voltage to the ECM.

I've notice that on a lot of schematics the PATS wires are absent.

Its not impossible but it'll take a bit of work.
 
#9
With your computer coming out of a 95 it should be able to be " made " to work. The 95 mustangs didn't have PATS according to quick google search.

The computer controls fuel pump prime and injector pulse....but if the furl pump relay isn't grounding then it won't start. There's a module under the steering column that relays the key info to the computer. I don't know if that sends a signal to the security light in the dash.

You'd need to check at the engine for injector signal. If the noid light flashes then half the battle is won. The other half involves getting the ground trigger signal from the engine computer to the fuel pump relay.

To my knowledge PATS still allows the computer to be read when a bad key is turned in ignition. ( I've scanned vehicles with bad keys in the past ). That means the computer turns on when key is in run regardless. The question is does the computer see the crank position if the key doesn't read ? If it kills the computer while cranking it won't start. Hence the noid light test for injector pulse. You'll also need power to the coil. If everything has power, except the fuel pump, it isn't hard to bypass and cut the pump on to start your car

If this computer is a 96....( with a late 95 build date ) it may be a PATS computer. That would mean you are doomed because the PATS actually talks to 96 and up computers

What's the code on your PCM ?

I'd look at the pin out if that's a true 95 5.0 mustang computer. The computer only needs ignition on, crank, ground, tach, and a few things like the clutch / neutral park switch feed to come on and start. The pump runs off the computer through a ground that triggers the pump relay.

Usually, a neutral safety or clutch switch will cause a no crank condition.
 
#10
90sickfox said:
With your computer coming out of a 95 it should be able to be " made " to work. The 95 mustangs didn't have PATS according to quick google search.

The computer controls fuel pump prime and injector pulse....but if the furl pump relay isn't grounding then it won't start. There's a module under the steering column that relays the key info to the computer. I don't know if that sends a signal to the security light in the dash.

You'd need to check at the engine for injector signal. If the noid light flashes then half the battle is won. The other half involves getting the ground trigger signal from the engine computer to the fuel pump relay.

To my knowledge PATS still allows the computer to be read when a bad key is turned in ignition. ( I've scanned vehicles with bad keys in the past ). That means the computer turns on when key is in run regardless. The question is does the computer see the crank position if the key doesn't read ? If it kills the computer while cranking it won't start. Hence the noid light test for injector pulse. You'll also need power to the coil. If everything has power, except the fuel pump, it isn't hard to bypass and cut the pump on to start your car

If this computer is a 96....( with a late 95 build date ) it may be a PATS computer. That would mean you are doomed because the PATS actually talks to 96 and up computers

What's the code on your PCM ?

I'd look at the pin out if that's a true 95 5.0 mustang computer. The computer only needs ignition on, crank, ground, tach, and a few things like the clutch / neutral park switch feed to come on and start. The pump runs off the computer through a ground that triggers the pump relay.

Usually, a neutral safety or clutch switch will cause a no crank condition.
Click to expand...

T4MO (PCM) it came out of a 94 Manual Gt. The engine cranks strong and I didn’t have started fluid so a used some MAF cleaner and it started right up. I have the 94-95 PCM harness, and engine harness installed. But the dash is still original to the 98’ 3.8L engine.

But my fuel doesn’t make a sound. But I will do the noir light test.
 
#12
T4MO is identical to my factory-installed '94 GT 5.0 w/M.T. The subscript following the PCM part # 12A650 is EA for manual trans., BA for automatic. If that PCM is being used, there should be no question at all of a PATS issue: PATS did not yet exist then.

However, in 5.0s from Explorers, PATS WAS used, so use of Ex PCMs results in PATS issues.

IMO, something is preventing pump operation. Electrical problem. Some harnesses actually had a fusible link in them feeding the pump. I would try "hot wiring" to the pump to see if it runs. imp
 
#13
Regarding PATS: My understanding is that in late '90s Ford PATS disabled only the injectors. This allowed an unsuspecting owner to drain a battery cranking using a non-chip key. Later years disable cranking (AND maybe other functions, I dunno about that). imp
 
#14
imp said:
T4MO is identical to my factory-installed '94 GT 5.0 w/M.T. The subscript following the PCM part # 12A650 is EA for manual trans., BA for automatic. If that PCM is being used, there should be no question at all of a PATS issue: PATS did not yet exist then.

However, in 5.0s from Explorers, PATS WAS used, so use of Ex PCMs results in PATS issues.

IMO, something is preventing pump operation. Electrical problem. Some harnesses actually had a fusible link in them feeding the pump. I would try "hot wiring" to the pump to see if it runs. imp
Click to expand...


That’s what I was thinking about just running a kill switch until I swap in the dash harness. But it’s not the pcm killing it. Pats acts between the ignition transciever and the pats module which is located over the indash fuse panel. My dash harness is slightly different from the 94-95 3.8 and 5.0 dash.

Since the voltage ran to the pump doesn’t change this weekend before I send my tuner off to american muscle I was going to hardwire the pump with a fuse and a kill switch that would only activate off of the ignition wire.

If anyone has any more input until then every piece of knowledge you all have shared has helped me immensely. And I’ll post a link to the YouTube video once it’s done but if any one figures it out before me you’re much appreciated lol.
 
#17
First, check for voltage and ground at the fuel pump relay. The computer triggers that relay through the ground side. If something in between the computer and the fuel pump relay is causing the signal not to get to the relay then a simple overlay will fix your problem. Find the correct pin for the fuel pump activation from the computer. Tap in to that wire and run it over to the fuel pump relay ground trigger pin.

Edit; I did some research. Isn't the 98 3.8 fuel pump relay built in the CCRM ? The CCRM also houses the ECU power relay. They started in 94. The v8 CCRM part # ends in 20...the 98 v6 CCRM ends in 03. They may not be compatible.
 
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#18
90sickfox said:
First, check for voltage and ground at the fuel pump relay. The computer triggers that relay through the ground side. If something in between the computer and the fuel pump relay is causing the signal not to get to the relay then a simple overlay will fix your problem. Find the correct pin for the fuel pump activation from the computer. Tap in to that wire and run it over to the fuel pump relay ground trigger pin.

Edit; I did some research. Isn't the 98 3.8 fuel pump relay built in the CCRM ? The CCRM also houses the ECU power relay. They started in 94. The v8 CCRM part # ends in 20...the 98 v6 CCRM ends in 03. They may not be compatible.
Click to expand...

I have the v8 CCRM
 
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