engine harness question

escortluver19 · Post by **escortluver19** » October 27th, 2006, 12:04 pm

im knee deep in my kl swap on my escort.I ended up pulling the whole harness out from the fusebox to the ecu.I noticed the whole charging system and basically all the wiring under the hood was in the same bundle of wires so i got rid of everything.Im goin to be using a mx3 gs harness so i have a few questions.Is the mx3 harness also bundled all together with the charging system attached in one big bundle? I cant seem to figure out if i need to cut the harness apart and use the stock escort chargin harness or if i can just use the whole harness from the gs and basically hook up my grounds and be good to go.My next question is, are the mx3 manual shifters and stabilizer bars the same?My last question is, when i pulled the ecu out of the escort i had to unhook two relays and a couple other connectors, so does the mx3 have these same relays and do i need them? I know these questions are kinda out of place on this forum but i figured you mx3 guys would know more than the escort guys since i will be putting the gs harness in.Any help would be appreciated.

PATDIESEL · Post by **PATDIESEL** » October 27th, 2006, 5:45 pm

The MX GS has the charging system in the main harness bundle, yes. So use the whole MX main harness and you should be fine. You might also need to swap the main fuse boxes and any other accessory stuff like relays and any other things that are attached to the MX bundle. It should be easy enough to figure out though. Start by installing the MX bundle through the firewall, start hooking things up and see what you have left over. Find out what the wires that are left over are for and then it should be simple enough to know whether they are necessary or not.
Mx shifter are different form pre 93 and post 94, so you'll need to check into which you need for the Escort.
The last ? would be for someone who knows about Escorts. Since I doubt any of us know what the relays are for in the Escort we cannot tell you if you will need them with the KL motor and MX harness. As mentioned above you should be able to figure out what you have left over and what is needed after you finish hooking up the motor stuff. The dash harness is pretty much on its own, but does go to some engine bay sensors such as the neutral switch and the back-up lights. Without a good write up I doubt you are going to find your answers here. However, those things shouldn't be too hard to figure out when you get the main stuff finished.

Tunes67 · Post by **Tunes67** » October 27th, 2006, 5:57 pm

I am in agreeance with Pat on all points but would like to add a couple of little things. While the charging system is indeed part of the main harness.. it sucks. You dont have a main + cable leading from the alternator postitive feed directly to the battery. It goes to the fuseblock and gets split off from there. This is an inefficient design in my mind.. I corrected it by running my own 4 gauge cable from the alternators positive feed to the battery directly. I speculate that it probably runs this way so the ECU can keep tabs on the battery's charge level. But I dont know for certain.. but that seems about the only reason I can think of that they did it that way.. either that or the wiring harness was designed by mitsushitsi (I have no proof of this though) so it wouldnt have to follow any kind of real world logic if that is indeed the case.

As for those 2 relays.. one is likely going to be your fuel pump relay.. but Pat is right its more a question for the Escort guys. Best of luck on your project.

Tunes67

escortluver19 · Post by **escortluver19** » October 27th, 2006, 10:42 pm

thanks for the help guys...i know more now than i did before.I kinda figured the one question couldnt be answered here but i thought id ask since it was on my mind.So you both agree that i can just run the whole harness from ecu to fusebox to motor? I guess ill have to see when i get the parts car and then post more questions if i have trouble.Thanks again.

max kl · Post by **max kl** » October 27th, 2006, 11:21 pm

Tunes67 wrote:I am in agreeance with Pat on all points but would like to add a couple of little things. While the charging system is indeed part of the main harness.. it sucks. You dont have a main + cable leading from the alternator postitive feed directly to the battery. It goes to the fuseblock and gets split off from there. This is an inefficient design in my mind.. I corrected it by running my own 4 gauge cable from the alternators positive feed to the battery directly. I speculate that it probably runs this way so the ECU can keep tabs on the battery's charge level. But I dont know for certain.. but that seems about the only reason I can think of that they did it that way.. either that or the wiring harness was designed by mitsushitsi (I have no proof of this though) so it wouldnt have to follow any kind of real world logic if that is indeed the case.

As for those 2 relays.. one is likely going to be your fuel pump relay.. but Pat is right its more a question for the Escort guys. Best of luck on your project.

Tunes67

do you asume the purpose of an alternator is to charge the battery?
the alts job is to replace to current the electrical system is using. the system is very effecent the alt sends current to the load of the car running and the battery at the main fuse box. the car gets its needed curent to run and has priority over the battery.
if the stock charge wire i croded or torn internaly than yea its inefficient .
and if you ad load to the battery post from a system or other accesory than yea the extra cherge wire helps but only if you have a voltage drop in the stock charge wire.

and dont forget current needs ground as much as positive flow.
if you ad a extra charge wire you are waisting you time if you dont ad a ground wire.

this is a rant but i dont want a general rule coming fom a post like that.

Tunes67 · Post by **Tunes67** » October 27th, 2006, 11:50 pm

this is a rant but i dont want a general rule coming fom a post like that.

You know.. for someone who doesnt want to be judged because he cant spell.. you sure got judgemental on me. So here is my rebuttle. If I made a wrong assumption about the charging systems of the MX-3 its because my experiences with them have been far less than positive so far to date. The function of the alternator is to maintain the charge of the battery and to supply power to the vehicles electrical system as needed. Power demands are monitored by the ECU. That is why there is a wire going from the alternator to the ECU. This signal wire is utilized by the ECU to tell the voltage regulator of the alternator when to ramp up for increased power demands. Now.. if you have a slow response from the voltage regulator and alternator on when to increase the power output.. where do you think the system is going to get the power from in the mean time? Thats right.. it will get the additional power needed from the battery. I have added extra ground wires and an extra positve feed wire to my RS and noticed better reaction to sudden increased power loads. Like when you step on the brakes when your headlights are on. The lights used to dim for almost a full second. Upgraded power cable & upgraded ground cables and replacing the signal wire in the wiring harness and replacing the alternator have resulted in my lights dimming for such a brief moment.. you have to be concentrating to see it. So if you disagree with my terminology.. fine. If you want to dispute my findings.. fine. But the fact of the matter is this.. if the system was designed efficiently as you so freverently claim.. then why are there so many issues with said charging systems? Rather than point out how wrong I am.. why dont you post up some solutions? Back when these cars and wiring harnesses were new.. the charging system and power harness worked fine. But it didnt take into account the additional voltage drops and current draw of the system as the harness aged and corroded. Since it didnt take this into account.. it is NOT an efficient design. The additional things I have done and put in place on my RS have offset this and returned my cars charging system to higher effciency. You may disagree with me all you want.. I really dont mind.. but dont insult me when you do so.

Tunes67

max kl · Post by **max kl** » October 29th, 2006, 1:21 am

no judgement . just dont want to have customers requesting a jumper wire fix to stop there head lights from dimming every time the bass hits . at my shop or any shop. i want nbs to understand why you would add the wires and not get all pissed when i do work and it dose nothing for there car.

mabey the wirring lasts longer in texas . i work on tons of older mazdas and only have dimming head lights from ground probs & big systems.

but dont be mistaken i am an anal a--hole.

PATDIESEL · Post by **PATDIESEL** » October 29th, 2006, 1:43 am

Acutally it is a bit of both and a bit of neither. The battery is a MUCH cleaner source of power for the car's electronics as it will flow a constant 12 volts and the necessary amps. The alt on the other hand is variant on its amp output and is delayed by the ECU having to recieve the requirements and then relay to the alt what amount of power is needed. So that running the alt to the battery and then from the battery to the fuse box is a better idea. However, running a larger power wire is negated unless a larger ground is run also. The power wire will only feed as much power as can be sent through the ground wire.

Tunes67 · Post by **Tunes67** » October 29th, 2006, 2:16 am

mabey the wirring lasts longer in texas

Considering texas is dry and arid for the most part.. that would be a no brainer. I doubt you see the corrosion in the wiring harnesses that I have up here in Washington state. I would also bet the canadians see even more corrosion in their harnesses than I do.

Tunes67