2.9 to 4.0 swap electrical wiring question! PLEASE HELP?

[Rhinehart5]

Try this.....

Drive the truck and see how hot the PCM gets (it doesn’t)....

Seal it in a box. Make a vent tube if you feel safer...

Ok sorry I was unaware like I said in my original post I’m no electrician and i wasn’t sure what to do hence the reason I came to this page to ask for help. I just don’t wanna ruin my computer

 

[NakedDucks]

No problem. And if it comes down to it, I have another computer.

But cutting wires to a PCM and extending them around 5 feet is NOT a good idea!!

 

[Curious Hound]

No problem. And if it comes down to it, I have another computer.

But cutting wires to a PCM and extending them around 5 feet is NOT a good idea!! View attachment 68439

Especially using butt splices like that.

 

[fastpakr]

Especially using butt splices like that.

Exactly. I don't have any concerns about properly extending a harness as needed with good soldered and sealed connections. Butt splices are asking for disaster.

 

[NakedDucks]

Exactly. I don't have any concerns about properly extending a harness as needed with good soldered and sealed connections. Butt splices are asking for disaster.

Even a soldered connection isn’t good in this case. Extending a harness for around 5 ft (about what he would need to extend it to be) creates 2 soldered connections (resistance) in the circuit... also, the thickness of wire will NEVER be the same as the original.... same gauge, yes, but even then, thicknesses vary.... and you again create a flow rate problem...

It’s best not to cut and extend it in this situation.

 

[fastpakr]

I'm sorry, but that's nonsense.

Put in two good connections and the change in resistance is minimal.

Use good 18 gauge wire and the added resistance is in the hundredths of an ohm over several feet.

This isn't rocket science.

 

[Curious Hound]

I'm sorry, but that's nonsense.

Put in two good connections and the change in resistance is minimal.

Use good 18mm wire and the added resistance is in the hundredths of an ohm over several feet.

This isn't rocket science.

I agree. The resistance change would be negligible. And since those conductors are carrying such little current, it really wouldn't matter.

Since he has two harnesses, I would scavenge wire from the extra harness to make the extra length, keeping the connector pins on thos pieces. That way, I'm only making one soldered connection per conductor. I would have complete faith in it.

 

[NakedDucks]

I agree. The resistance change would be negligible. And since those conductors are carrying such little current, it really wouldn't matter.

Since he has two harnesses, I would scavenge wire from the extra harness to make the extra length, keeping the connector pins on thos pieces. That way, I'm only making one soldered connection per conductor. I would have complete faith in it.

If you and Fastpakr feel comfortable doing it, then by all means.... do it.

But PCM’s, ECU’s, TCM’s, BCM’s and thing like that DO in fact measure reference voltages, voltage drops, ohms, and ohm drops..... and when they see problems, they lock codes, shut down systems, and respond poorly (if at all).

One bad soldered joint, and your chasing your tail for HOURS to find it.

Is it possible? Yes.
Safe? If done right... yes
Would I do it to a major controlling module? No.

 

[fastpakr]

If you and Fastpakr feel comfortable doing it, then by all means.... do it.

But PCM’s, ECU’s, TCM’s, BCM’s and thing like that DO in fact measure reference voltages, voltage drops, ohms, and ohm drops..... and when they see problems, they lock codes, shut down systems, and respond poorly (if at all).

Did you read this entire thread and somehow come to the conclusion that you were the only person intelligent enough to know that?

 

[Rhinehart5]

Thst

I'm sorry, but that's nonsense.

Put in two good connections and the change in resistance is minimal.

Use good 18mm wire and the added resistance is in the hundredths of an ohm over several feet.

This isn't rocket science.

that’s what I planned to do was buy new wire same gauge and solider it together and use shrink wrap and the connections and run approx 5 foot to opposite side of the cab and solder the pig tail of wires to the computer plug and shrink wrap and then use lume snd snd electrical tape to make it look nice and run along the firewall because the computer on my 2 trucks neither one is exposed to rain or water or the elements like the nakedducks guy is saying and I’m worried about it getting hit if I seal it up in a small air tight box but he’s got me worried I’m gonna screw up the computer and have problems extending the harness

 

[Rhinehart5]

Thst


that’s what I planned to do was buy new wire same gauge and solider it together and use shrink wrap and the connections and run approx 5 foot to opposite side of the cab and solder the pig tail of wires to the computer plug and shrink wrap and then use lume snd snd electrical tape to make it look nice and run along the firewall because the computer on my 2 trucks neither one is exposed to rain or water or the elements like the nakedducks guy is saying and I’m worried about it getting hit if I seal it up in a small air tight box but he’s got me worried I’m gonna screw up the computer and have problems extending the harness

Hot not hit sorry autocorrect

 

[Curious Hound]

Ok. Here are the numbers.

18 gauge wire; resistance is 5.8 - 7.8 ohms per thousand feet. So, adding 5 ft of wire increases the circuit resistance by 0.029 - 0.039 ohms depending on temperature.

16 gauge wire; resistance is 3.7 - 4.9 ohms per thousand feet. So, adding 5 feet of wire would add 0.0185 - 0.0245 ohms depending on temperature.

I really doubt that the ecu circuits are sensitive enough to detect that. Your multimeter definitely is not. Make good clean solder joints and use heat shrink with sealant in it to keep moisture our.

If that feels like to much risk, just use the short harness and put the ecu in a waterproof box. It's all up to your comfort level and budget.

To put that in perspective, if a sensor circuit is running 30mA (0.03amps), then at about 0.035 ohms, your wire extension has dropped the voltage by 0.00105 volts.

 

[NakedDucks]

Did you read this entire thread and somehow come to the conclusion that you were the only person intelligent enough to know that?

That’s cute how you only quoted a small bit of my reply instead of all of it.

 

[Rhinehart5]

Ok. Here are the numbers.

18 gauge wire; resistance is 5.8 - 7.8 ohms per thousand feet. So, adding 5 ft of wire increases the circuit resistance by 0.029 - 0.039 ohms depending on temperature.

16 gauge wire; resistance is 3.7 - 4.9 ohms per thousand feet. So, adding 5 feet of wire would add 0.0185 - 0.0245 ohms depending on temperature.

I really doubt that the ecu circuits are sensitive enough to detect that. Your multimeter definitely is not. Make good clean solder joints and use heat shrink with sealant in it to keep moisture our.

If that feels like to much risk, just use the short harness and put the ecu in a waterproof box. It's all up to your comfort level and budget.

To put that in perspective, if a sensor circuit is running 30mA (0.03amps), then at about 0.035 ohms, your wire extension has dropped the voltage by 0.00105 volts.

Thank you! And one last thing if I decide to do a water proof box would I need to worry about venting it or anything like that? I’m not sure if the computer even gets warm or anything but I was wondering if it might cause it to over here when it’s air tight and no ventilation??

 

[Curious Hound]

I don't have a good answer for that. I don't think the factory location has any vent. But I've never looked at it closely. I believe Ford sealed it to keep water out. If you do your own box, mount it as far away from heat sources as possible. But the whole engine compartment gets hot in my opinion. There is something under the hood that has rapid-fire explosions happening inside it and heat is a byproduct.