Lots of codes, engine runs alright though

[cp2295]

Okay so I did the 3.0 to 4.0 swap and had to kind of rig up the 3.0 wire harness as there were no 4.0 manuals at the junkyard. The truck runs alright but it's got quite a few codes:

P0340 cam position sensor circuit a; some background on that: my 3.0s harness was a 2 pin cam sensor. The 4.0 has a 3 pin, but the extra wire was black and white and ground according to my manual so I just ran some wire straight off the sensors b&w wire to a body ground. The other two wires were the same color so I hooked up accordingly.

P1451: canister vent solenoid circuit bad

P0135: o2 sensor heater circuit; I had to lengthen the wire on the O2 sensor connection (just extended the sensors wire) maybe that screwed something up?

P0155: o2 sensor heater circuit

P1409: egr solenoid circuit malfunction

I had to extend wires for certain sensors, I double checked they were all wired the same when I hooked it up, haven't checked it since these codes. This is the first time I've heard this engine run and everything so I have no prior knowledge to how it ran or what codes it had, etc

 

[cp2295]

Went down to the library and got some wiring diagrams from the 1999 3.0 & 1998 4.0. Shows all the o2 sensors, cmp sensor, egr vacuum solenoid, and the canister vent solenoid all being spliced together (all are orange and light blue). From what I see the only way these get grounded is through the cmp sensor (through its ground wire). I took apart the 4.0 wire harness I had and found this to be true.

The 3.0s harness shows that the cmp sensor is not even connected to these other sensors, and of course there's no ground wire attached. It instead connects to some other wires, but the main wire that supplies the cmp with power from the PCM is the same on both harnesses, and goes into the same pin (85).

So I'm concluding that the cmp needs to be spliced into this connection of all the light blue and orange wires to complete the circuit. The orange and light blue wire goes into the power distribution box, so every sensor minus the cmp is getting power, however the cmp grounds the others. I will keep the one wire grounded to the body. I saw in the 4.0s harness it goes into a splice of 6 grounds which then gets taken by one big ground. The 3.0s harness grounds these wires the same way just is missing the cmp sensor so I figure it won't need to be spliced in, if it does then I will splice her in.

Will post up later if it works out or not

 

[RonD]

Yes, 3.0/4.0 had similar wiring.

Yes, almost all engine controls and sensors get 12volts when the EEC relay is closed(EEC relay is activated by the Key)
So they all share a common 12volts/splice.
The computer uses the grounds for control on many of these, so the "ground" wire is a control wire, so should not just be grounded to a common ground.
On some grounds at the computer the "ground wire" is also a reference "voltage"(0 volts/ground is a voltage) so needs to be "grounded" at the computer terminal/port assigned to it.

Ford used two different CPS(cam position sensors), Hall effect and Variable reluctance.
I would look up each and make sure the computer will understand the one you are using.
The CPS isn't needed for the engine to operate, if computer is getting no CPS data or bad CPS data it will use Batch Fire, on a V6 it fires 3 injectors at the same time, instead of Sequential fire, Batch fire is similar to the way a carburetor worked, intake is just kept full of fuel/air mix and the open intake valve sucks it in, this, of course, lowers MPG.

The computer monitors the O2 heaters, I would check the fuse first, heaters have their own fuse.

 

[adsm08]

Did you use the 4.0 harness or the 3.0 harness?

 

[cp2295]

3.0 harness, I got the 4.0 (1998) with the harness (dude just left everything on there because he did a 5.0 swap and gave me literally everything on the engine). Anyways it was for a auto tranny setup. I have a manual tranny though, so I got a computer at the junkyard from a 1998 manual tranny ranger 4.0. I didn't take the harness, I thought I could just leave the plugins for the auto tranny hanging (save a couple bucks and some time). Well I tried turning it over and it wouldn't turn over. So I took my 3.0s harness and plugged it in and it made the engine turn over. So I spliced and lengthened wire on my 3.0s harness to accommodate for the sensor location. So I got it all hooked up and everything and turned it on. Fired right up, however I immediately got all the codes I listed.

As I said I ran into the issue of the cmp sensor, every other sensor had the same color wires though, just the cmp was different. So I did that thing where I spliced the cmp into the orange and light blue wires (I just tapped in at the egr sensor because it was closest and I had that wire extended anyway). Turned it on and my codes are back..

I am going to tap into the ground that it would be wired into from the factory via the maf sensors black wire (it goes straight into the splice of all the grounds). Hoping it'll work out.

Ron which fuse am I looking for? It's in the power distribution box right?
I did accidentally screw up when extending the o2 sensors wires, I just cut right through both of them before realizing there is two white wires so I just spliced it together how I thought it was and then I connected it, maybe I blew a fuse because of that.

 

[cp2295]

The computer uses the grounds for control on many of these, so the "ground" wire is a control wire, so should not just be grounded to a common ground.
On some grounds at the computer the "ground wire" is also a reference "voltage"(0 volts/ground is a voltage) so needs to be "grounded" at the computer terminal/port assigned to it.

So you are saying that I should ground it the way they had it from the factory and tap into the splice of all those grounds? Instead of just grounding it on the body..

I noticed that 5 wires from the PCM go into that splice, then one from the cmp and one from the maf come in from the other way. A big fat wire goes from that connection towards the fuse box (it goes into that big square plug in on the driver side of the intake) I didn't follow it after that I just saw that it went to that plug in and assumed that it was the ground wire since it was much fatter than the others.

The 3.0 and 4.0 harness has the same ground routing according to the wiring diagram I got (it is pretty nice actually, gotta love the library for that), just in the 3.0 it doesn't have the cmp attached into that splice. All the other wires are in that splice though.

 

[cp2295]

According to the ford diagram the engines fuse box has a relay for the cmp, egr vacuum solenoid, canister vent solenoid, and heated oxygen sensor. All of which I'm getting codes for and only these things. Has to be something with that wire, or fuse.

 

[RonD]

I looked at a 1995-1999 3.0/4.0 Ranger wiring diagram at autozone's online guide.
No such relay's were shown, and I can not see a reason to have relays for those devices.

The one EEC(PCM) relay supplies 12v to most when key is on

The heated O2 wires could have a relay since they have a separate wiring path and fuse, but it is not shown in the diagram I looked at.

 

[cp2295]

Well there is an orange and light blue wire which connects them all and splices together at splice 109 on the 4.0. That wire goes to the power distribution box and hooks into fuse in position 13 (according to the diagrams I got)

 

[cp2295]

That fuse is melted, gonna rewire that ground, replace the fuse and should be good to go

 

[cp2295]

No more cel! Replacing the fuse and grounding it correctly did the trick. Thanks Ron