Pats module bypass?

cp2295 · Jan 16, 2017

Hi everyone I have a 99 ranger, with a 4.0 and ecu swapped in from a 98. I lost my keys up in the woods (ranger wasn't with me) and of course lost my only transponder key. I have a steel key still and have been able to get the rig started by turning the key to the on position, and then jumping the starter relay. Since it's a 98 computer it still sends power to the fuel pump, however it won't let the starter crank. Just wondering if there's a way I could feed power to the ignition switch so my starter will crank when I put the ignition to the start position. I'm skeptical about spending $120 on 2 keys so the locksmith can attempt to program the keys, but I don't think it will work since the ecu is totally different than stock.

If I have to I'm just going to wire a push button to the relay and use that, but I would like to try and avoid that.. Kinda hokey if you ask me but it may be my only option.

cp2295 · Jan 18, 2017

I have found some info on a relay box under the dash containing a starter interrupt relay for the anti theft system. I found the box but nothing is labeled, wondering if anyone knows has a diagram. Wondering too if anyone knows which wires need jumped but probably will have to just hit it with a test light and find out lol

Shran · Jan 18, 2017

I am under the impression the GEM module is what the keys are programmed to but I could be wrong. If that is the case then it doesn't matter what ECU you have installed.

RonD · Jan 18, 2017

Starter Relay in fuse box is Grounded by PATS system if Key passes the test.

Automotive relays are standard world wide, look here: http://www.reuk.co.uk/wordpress/electric-circuit/automotive-relays/

You will either have a 4 pin or 5 pin socket, relay only needs to be 4 pin but can also be 5 pin

85 and 86 are the Coil wires on all relays, when one has 12volts and the other is grounded the Relay will Close
There is no polarity, 85 can be 12v or 86 can be 12v, as long as the other one is grounded then relay will Close.

In 1999 when you turn the key to START that 12volts should go to pin 86, and if PATS is working and key passed the test then 85 would be a Ground and relay would close, relay closing sends 12volts, from ignition fuse, to starter motor and starter starts engine

So test which slot on the relay base is 12v when key is turned to START, 85 or 86
Then which ever is NOT 12volts, 85 or 86, cut that wire and Ground it, so no PATS ground is needed.

But it is very odd that fuel injectors work with no PATS key, PATS disabled fuel pump AND fuel injectors since day one of the system, starter interrupt was an add on in later years.
Fuel pump power is easily bypassed so not much of an anti-theft device, fuel injectors on the other hand is very very hard to get around

So I would check Fuse 24(7.5amp) in cab fuse box to see if it is good, that fuse is the power that actives the relay when key is turned to START, so you need no and have no PATS test, just a blown fuse

cp2295 · Jan 18, 2017

RonD said:
Starter Relay in fuse box is Grounded by PATS system if Key passes the test.

Automotive relays are standard world wide, look here: http://www.reuk.co.uk/wordpress/electric-circuit/automotive-relays/

You will either have a 4 pin or 5 pin socket, relay only needs to be 4 pin but can also be 5 pin

85 and 86 are the Coil wires on all relays, when one has 12volts and the other is grounded the Relay will Close
There is no polarity, 85 can be 12v or 86 can be 12v, as long as the other one is grounded then relay will Close.

In 1999 when you turn the key to START that 12volts should go to pin 86, and if PATS is working and key passed the test then 85 would be a Ground and relay would close, relay closing sends 12volts, from ignition fuse, to starter motor and starter starts engine

So test which slot on the relay base is 12v when key is turned to START, 85 or 86
Then which ever is NOT 12volts, 85 or 86, cut that wire and Ground it, so no PATS ground is needed.

But it is very odd that fuel injectors work with no PATS key, PATS disabled fuel pump AND fuel injectors since day one of the system, starter interrupt was an add on in later years.
Fuel pump power is easily bypassed so not much of an anti-theft device, fuel injectors on the other hand is very very hard to get around

So I would check Fuse 24(7.5amp) in cab fuse box to see if it is good, that fuse is the power that actives the relay when key is turned to START, so you need no and have no PATS test, just a blown fuse

The fuel pump works because it's a 98 ecu in a 99 chassis. 98 didn't have pats from what I understand, before with the 99 ecu the fuel pump would not work. (And probably the injectors too)

They are all 5 pin relays, and unfortunately they are not labeled 30, 85, 86, 87, and 87a. Just 1-5. But you're saying if I find which one is going to the anti theft module then just ground that wire and call it good? What if I found the pin that gets power when the key is in the start position and then do an ohms test to the "switched" pin on the actual starter relay under the hood and whichever pin goes to it from the interrupt relay under the dash, and then just took a jumper wire between the two?

RonD · Jan 19, 2017

Look at the slot/pin layout in the link, 85 and 86 slots are easy to ID
Only 3 slots run in the same direction, 85, 86, and 30, 30 will always be in the middle, so you can ID 85 and 86 that way
Test which one has 12v with key turned to START, the other one needs to be Grounded

You shouldn't need to do anything in the dash wiring, the 1999 2.5l Rangers didn't have PATS so starter relay was just Grounded at engine fuse box, you can do the same.
Running a 12volt wire is just duplicating what is already there, at slot 86

Diagram here in PDF

May be you can find the Dark Blue/Orange stripe wire coming out of engine fuse box, cut it and test that it IS slot 85, then Ground it, same as stock wiring without PATS

cp2295 · Jan 19, 2017

Awesome diagram Ron, makes perfect sense with that layout, I'll have to get in there and start going at it with a test light, thanks!

RonD · Jan 19, 2017

Yes, make sure 85 and 86 are "as labelled", wiring can be reversed for these without effecting anything UNLESS you are rewiring, lol, then it can, so test first

cp2295 · Jan 20, 2017

If I can't figure that out can I just take the start wire from the ignition switch to the starter relay in the engine compartment ?

RonD · Jan 21, 2017

cp2295 said:
If I can't figure that out can I just take the start wire from the ignition switch to the starter relay in the engine compartment ?

You already have that, the 12volt wire from ignition switch to starter relay, you are missing the Ground Wire

If you can find the Dark Blue/Orange stripe wire at PATS module then you can Ground that wire in cab

Blown · Jan 22, 2017

You can bypass PATS with a Tweecer tune, however it is no less expensive than having keys made. It could be an option if you had to also change other items and wanted/needed a tune for power adders. Just saying.

Good luck with the wiring, seems like the best fix for the money.

cp2295 · Feb 1, 2017

Found the starter relay wasn't grounded just like ur diagram said. So I just grounded it and it works perfect now thanks

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RonD · Feb 1, 2017

Good work

Thanks for posting the fix

RDC · Aug 13, 2017

RonD said:
Starter Relay in fuse box is Grounded by PATS system if Key passes the test.

Automotive relays are standard world wide, look here: http://www.reuk.co.uk/wordpress/electric-circuit/automotive-relays/

You will either have a 4 pin or 5 pin socket, relay only needs to be 4 pin but can also be 5 pin

85 and 86 are the Coil wires on all relays, when one has 12volts and the other is grounded the Relay will Close
There is no polarity, 85 can be 12v or 86 can be 12v, as long as the other one is grounded then relay will Close.

In 1999 when you turn the key to START that 12volts should go to pin 86, and if PATS is working and key passed the test then 85 would be a Ground and relay would close, relay closing sends 12volts, from ignition fuse, to starter motor and starter starts engine

So test which slot on the relay base is 12v when key is turned to START, 85 or 86
Then which ever is NOT 12volts, 85 or 86, cut that wire and Ground it, so no PATS ground is needed.

But it is very odd that fuel injectors work with no PATS key, PATS disabled fuel pump AND fuel injectors since day one of the system, starter interrupt was an add on in later years.
Fuel pump power is easily bypassed so not much of an anti-theft device, fuel injectors on the other hand is very very hard to get around

So I would check Fuse 24(7.5amp) in cab fuse box to see if it is good, that fuse is the power that actives the relay when key is turned to START, so you need no and have no PATS test, just a blown fuse

Hello, I have a 1998 3.0 4x4 autotrans ext cab xlt Ranger without PATS. I replaced the blown motor with a 1999 3.0 from a flex fuel Ranger with a PATS system. I only used the 99 maf and it will start and run but not well, it shows error codes P0172,P1504,P0401,P1132,P1152,P0175. I can drive it everything works no problems other rough idle and the codes. I replaced the PCM with the one from the 99 flex fuel ranger and it will not start . Is there a pin out on the ecc/pcm that I can jumper or relay to get it to run ? Is it possible to remove the pats module from the 99 and install it on the 98 ? I am not sure but I understand that the injectors from the flex engine are a higher volume than the ones in the 98 and may be my problem with all the codes, most indicate running too rich . Do you think replacing the injectors to match the original pcm on the 98 would help ? Thank you .

cp2295 · Aug 25, 2017

I would just get a 98 pcm... Trying to add pats would be worse than removing it imo.. You can find a 98 pcm all day on ebay.

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Pats module bypass?

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