Explorer OBD2 Harness Re-work

[garberz]

Ok still confused the 14 gauge green wire I added to go to the inertia switch. Where does it go on the relay box?

It goes to pin #87 on the fuel pump relay. #30 gets power from the fuse. #85 can be powered from the same fuse, and #86 is the ground signal from the ECU. #85 and #86 are not polarity specific, so you can use either one. As long as one is 12v. and the other is ground from the ECU.

Mark

 

[904Bronco]

It goes to pin #87 on the fuel pump relay. #30 gets power from the fuse. #85 can be powered from the same fuse, and #86 is the ground signal from the ECU. #85 and #86 are not polarity specific, so you can use either one. As long as one is 12v. and the other is ground from the ECU.

Mark

You must have watched the video Mark... ;D

 

[EFI Guy]

It goes to pin #87 on the fuel pump relay. #30 gets power from the fuse. #85 can be powered from the same fuse, and #86 is the ground signal from the ECU. #85 and #86 are not polarity specific, so you can use either one. As long as one is 12v. and the other is ground from the ECU.

Mark

Mostly correct. You wouldn't want to power 85 (or 86) off of the same fuse as 30 which is battery power, 85 (or 86) should be hot with ignition only. You never want to power a circuit that the PCM grounds when the key is off, it can burn stuff up. This rule also applies to the check engine light circuit, overdrive light, etc...

Also, 87 needs to feed the fuel pump monitor circuit of the PCM as well as the inertia switch.

 

[garberz]

Mostly correct. You wouldn't want to power 85 (or 86) off of the same fuse as 30 which is battery power, 85 (or 86) should be hot with ignition only. You never want to power a circuit that the PCM grounds when the key is off, it can burn stuff up. This rule also applies to the check engine light circuit, overdrive light, etc...

Also, 87 needs to feed the fuel pump monitor circuit of the PCM as well as the inertia switch.

Yup, I typed off memory without checking my notes. I have those on a keyed circuit like you said.

Mark

 

[Crackin1]

Ok that answers my question the green wire and green and yellow go to the same terminal.
Thanks

 

[Crackin1]

Ok one more why does the yellow and white alternator sense wire go out to the relay box and what do I do with it.

 

[904Bronco]

Ok one more why does the yellow and white alternator sense wire go out to the relay box and what do I do with it.

Most people hook it to the Alt Batt terminal and call it good.

But the better way is to hook it to a 12v power source away from the Alt so that it can sense the voltage... (I am not doing justice the explanation that Broncobowsher gave on another thread.)

Do you have a 12v Batt source at the box that you can easily attach it to?
-------------------------------------------------------------------------------------
Broncobowsher:

"The "A" is often just tied back into the output post. But it should really be run back to the battery. It is the wire that is used to measure the battery voltage and adjust the regulator to get the desired output. The I turns it on, it needs to be switched or else the alternator will run the battery down trying to get output from a non-spinning alternator."

 

[sstclair]

What are people running with the 5th relay? I saw one labeled "Start" in David's picture. Seems like running a start/run signal might be a good idea and ease some load on the ign switch. We're using AC on the one we're building. Seems like it might be useful for that too.

 

[chuzie]

If anyone building an EFI setup is in need of some Carter P4070 pumps, I just posted a couple for sale in the classified section.

 

[EFI Guy]

What are people running with the 5th relay? I saw one labeled "Start" in David's picture. Seems like running a start/run signal might be a good idea and ease some load on the ign switch. We're using AC on the one we're building. Seems like it might be useful for that too.

You can use the 5th relay slot however you like. I like to add a relay to the start circuit on the 98 and later with 4r70w (they have smaller start circuit wiring). They will trigger a fender mounted solenoid just fine, but I would not trigger a starter mounted solenoid with the factory start circuit wiring.

Sometimes I'll use it for the reverse light circuit or I'll use a relay slot to hold the diode. It really just depends on the harness I'm building and what fuse/relay box I'm working with.

 

[sstclair]

Thanks Garry, it is a 2000 harness I'm using with the 4r70. I also opted for the aftermarket fuse/relay box. It's been fun using your notes and videos. You'll be getting an ECM or two to flash in the near future. It's really nice to know there's somebody out there that we can fall back on when we need to.

 

[JSmall]

Can VSS and OSS be removed if running a manual trans? I assume so since both plugs are in the trans harness. Thanks

 

[Rabee]

Hi Garry
Thanks for the great instructional work!

I have 1996 explorer 5.0 as donor car
I am almost ready to remove engine for my engine swap project (mercedes w123 300TD)


I will use T5 or TKO transmission...

My question is about the wiring harness.

I am taking the engine and the transmission wiring harness so I can separate the front oxygen sensor’s harness and I’m also taking the inertia switch and the OBD II.

I wonder what other interior harness I need to take with me?
I’m also taking the instrument cluster with its wiring in case needed

Thanks
Rabee

 

[sykanr0ng]

Hi Garry
Thanks for the great instructional work!

I have 1996 explorer 5.0 as donor car
I am almost ready to remove engine for my engine swap project (mercedes w123 300TD)


I will use T5 or TKO transmission...

My question is about the wiring harness.

I am taking the engine and the transmission wiring harness so I can separate the front oxygen sensor’s harness and I’m also taking the inertia switch and the OBD II.

I wonder what other interior harness I need to take with me?
I’m also taking the instrument cluster with its wiring in case needed

Thanks
Rabee

Grab the inertia rollover switch and pigtail from the right corner of the passenger foot-well under the carpet.

 

[Rabee]

Inertia switch plus its pigtail grabbed already.
OBD 2 port with its wires taken too.

I wonder if I need to keep VSS connector and wiring as I am going to use either T5 or TKO?

 

[EFI Guy]

Can VSS and OSS be removed if running a manual trans? I assume so since both plugs are in the trans harness. Thanks

They can both be removed as long as you are removing EGR and EVAP as well. VSS is needed for them to function. The only other reason you might want a VSS is for cruise control.

Inertia switch plus its pigtail grabbed already.
OBD 2 port with its wires taken too.

I wonder if I need to keep VSS connector and wiring as I am going to use either T5 or TKO?

See above on the VSS. Don't forget the firewall harness.

 

[JSmall]

They can both be removed as long as you are removing EGR and EVAP as well. VSS is needed for them to function. The only other reason you might want a VSS is for cruise control.

Thank you, Gary!!

 

[JSmall]

My 97 has a PCM code of XDT2. I want to grab another PCM at the JY so I can send both to you at the same time. Does XDT2 interchange with any other PCM codes?

Thanks,

 

[Rabee]

I will keep EGR, but removing EVAP.
So I guess VSS should stay. However, I wonder where to plug it in a manual transmission?

Yes I am taking the entire firewall harness. Not under the dash harness.

Do I need ignition switch and key assembly?
The engine will go into W123 Mercedes, not a bronco.

Thanks you

 

[73azbronco]

I will keep EGR, but removing EVAP.
So I guess VSS should stay. However, I wonder where to plug it in a manual transmission?

Yes I am taking the entire firewall harness. Not under the dash harness.

Do I need ignition switch and key assembly?
The engine will go into W123 Mercedes, not a bronco.

Thanks you

Wouldn't it be easier to fix the merc?