The wiring harness that came on my 7 is missing one of the four main connectors that are located under the dash. The previous owner swears the 7 ran really good using that harness.
This second picture is of one of the connectors that are under the dash. It is the harness that came with the 7. It has the two connectors that go to the ECU and another up higher and is missing the orange connector.
The first pic is of the harness that I'm using now. It has all four connectors on it. Two go to the ECU and 2 go toward the dash.

Now the question: What is the connector for that is missing on harness that the PO was using? Is it not needed?

[ATTACH][/ATTACH]


Thanks, ashley

 

I have the wiring diagrams but I really can't tell which harness would connect to the emissions harness. Engine harness?
I think one harness must be from an NA and the other one from a Turbo. Or not.

 

I think I found it. It must connect to the Front Harness. So if the original motor was using this EM harness and it doesn't have a connection to the Front Harness, what does that mean?
Should I switch back to that harness since I was told it worked great and I can't seem to get this thing running now?

 

What series car? What year car? Matters.

Sounds to me like one is a series four harness and the other a series five.

The attached jpg is of someones EM harness and it is a series FOUR. Matters not turbo or non turbo, both configured the same.

Series five ain't a lookin like that series four jpg. Both non turbo or turbo series five look the same plug wise in the areas your interested in.

 

I have a gxl / t2 swap. Its an 1990 S5. The previous owner blew the NA engine and then did the S5 to S5 swap. But, he put a 3 inch exhaust system on it and proceeded to blow the T2. I bought the car and swapped in another 1990 T2 using the harness that came with the motor. That would be the pic with all 4 of the connectors.
I've had the 7 since Oct and I've never been able to get it run correctly.
Now it has the 3 inch exhaust, RTek 1.7, 720 cc injectors, Walbro fuel pump, swapped out the CAS, swapped the ECU (3 times), did away with the MOP and premix now.

Both harness' connect to the ECU but the one that came with the 7 is missing one connector.

For a couple of months, the 7 would start and idle but would not go down the road, everybody thought it was "limp mode" thus the pre-mix and RTek. Then everybody thought it was the ECU. First the MOP fried the ECU (twice), I replaced MOP and then the ECU fried the MOP. $575 in ECU's and $100 MOP. and still doesn't run.
Now it will start but keeps backfiring until it finally dies. Will not idle.

 

The harness with the missing connector most probably was from a JDM or jap engine and the reason for that would be their EM harness does not carry the wiper motor wiring. Talking series five harness and car.

The JDM harness will not fit the car as good as a USA EM harness ...from what I"ve read. It being a right hand drive vehicle so the routing would be different therefore if put on a USA car *adjustments* have to be made to the routing and also wiper wiring has to be installed or taken out of the old USA EM harness to make the wiper motor work. That's my GUESS for the day.

Wiper wires colors are: Blue, Blue/Red, Blue/White, Blue/Yellow.

Then again it's all guessing with me and series five. Tell you what, look at the attached jpg. Look at the plugs in Green and the plug in Blue. The plug that is missing on one of the two harness, does it have the wire colors shown on my jpg? The two plugs are called X-10 and X-11. IF it does then we can tell what your missing on the harnesss without that plug.

 

It might be JDM because it makes its initial contact with the engine on the drivers side and attaches to the other connectors from there. It actually wraps along the firewall end of the motor first. The complete harness of course makes its initial contact with the engine on the passenger side. The shortest way.

If the PO used the JDM harness, would switching back to that harness make my engine run???

The wire colors that would be left unattached, don't match any of the connectors on the jpgs.
If it wasn't so time consuming, I'd just hook it and see what doesn't work that should.

Since the complete harness mates with the front harness, odes that indicate that its an NA harness?

If it is NA, shouldn't I just be able to plug it in and make it work since I have no emissions?

ash

 

Whether it's non turo or turbo it should mate and the engine should run without any catastoic thing happening if it's the same series. Series four won't fit series five and vice versa. I see no problem.

The harness for the wipers...............where does it originate from? ON YOUR car? Should be a part of the stk EM harness on the USA version. Sounds to me like he has a JDM harness on the car...............so the question arises.....how did he make the wiper motor work?

 

I hope I wasn't sold a $275 ECU that is damaged.

I couldn't get it to even start so I thought maybe I would just start over. I took off the UIM and removed all of the injectors, oil lines, vacuum lines and the whole rats nest. Now I'm going to finish removing the rest of the emissions and start with new vac lines and fuel lines. Just put it back together and see what happens.
Maybe if it doesn't start this time, I'll just part it out. Hate to give up on it but........

 

Sort of a general rule and quick check of the ECU would be to see if it has power on pins 1A and 1B and then see if the ref voltage is present. You can see ref voltage on say the TPS or OMP or boost sensors elect plugs> Its a brown/white wire and should have 4.5 to 5vdc if the key is on and 1A and 1B have power at the ECU.

If I had a ref voltage..................I'd put a spare CAS on the harness and put the key to ON and then spin the CAS bottom gear and listen for spark sound and injector clicking sound. Maybe lay one sparkplug wire at the Lead coil just barely in the coils bore and spin the CAS gear. Should see/hear a good spark if alls well with the ECU. The CAS gear does not have to be spun very fast at all to do this.

Assuming a bit here. Like the main relay is pulling in when the key is put to ON and there's power at the coil assys and EGI fuse is good in the engine bay (those two are a given if power is at pin 1A and 1B of the ECU.

 

There is an Atmospheric Presssure sensor located on the passenger inside Kick panel,that is connected to the series 4 ECU wiring harness on that side.
The Harness comes inside the car,and after the Grommet the ECU is hooked up(one big,one small connector) and another connector goes to the passenger side where that sensor is.I "think" the other one was not used.
Does that help you at all?

 

Does this still apply if it an S5? Mine is a 1990 gxl / T2 swap. The 7 is a 1990 and so is the engine.

 

Sorry,You'd have to get Hailer's opinion on that one,as I have only worked basically with 1986-88 models..
More useless info is,the s4 harness does hook up to the wipers,AWS and the cruise(if equipped),just before the firewall grommet area.
See if you can get Rotary Rocket 88 on this one,as he can tell you more about the "SWAP" aspect of it.
You should re-iterate that it is an s5 TII in a S5 N/A body?..so is it using a TII engine harness or a N/A engine harness?

 

you said you did away with the oil metering pump? how did you go about doing that? you said you have an Rtek? and you swapped out the ecu 3 times? do you have 3 Rteks laying around or did you actually go back to the stock ecu?

if you went back to stock ecu, then the s5 oil metering pump HAS to be connected in order for the car not to go into limp mode on you.

 

I didn't do the swap but the harness that I am using connects to the front harness and I think that makes it from an NA.

 

The OMP is still attached to the engine. I just unplugged the connections and I am using pre-mix.
I do have 1 extra RTek 1.7 laying around. I sent my ECU in and they chipped it. Sometime the OMP died and took the ECU with it but I didn't know the ECU was bad, I just knew the OMP was. So, I replaced the OMP. Then, the ECU fried the OMP, about this time I was told that probably the ECU was bad. So, I replaced the ECU and swapped the RTek chip to the new ECU but because the OMP was bad, it shorted out the ECU. Then, I was thinking, "this is crazy" and disconnected the OMP and replaced the ECU with one that somebody had already chipped.
Now it won't even start. It just backfires. Never quite catches, just boom, boom. boom.
This is my 5th 7 but its my first swap and definitely will be my last.

 

the omp has to be plugged in. the ecu will go into limp mode

 

I have the RTek 1.7 with the OMP override built in. It allows you to disconnect the OMP without getting any errors or going into limp mode.

I should have kept the 88 T2.

 

Just wondering what would happen if you just plug in the OMP and let it dangle on the side of the engine.??it may fix the "limp mode".(even if it is an Rtek,it may have fried the circuitry)
That is what they do when they OMP Delete on an S5.Since you can't rightfully take the omp out of the equation(and the ecu circuitry), IF you decide to go Premix and delete the omp, they just keep it hooked up and set it off to the side.

 

No external ATP on a series five. It's internal to the ECU itself. External ATP is only seires four.

Backfiring. That's good. Must have spark then which is good.

ECU part number N374?????? not good if so.

Got a non turbo series five you can plug in and try to start it? Should start and idle.

 

.

 

plug in the omp. then disconnect the battery to reset your electricals. it should start. just because you think the omp overide is on the ecu, doesnt mean it really is. car will not start or run without it being connected to omp....period

 

Got a non turbo series five you can plug in and try to start it? Should start and idle.[/QUOTE]

Its a N370. i tried a N374 with the Knight chip but it ran so rich that it would load up with fuel and die within secs so I didn't get a chance to see if it made any difference how it ran.
I'm going to start putting the vacuum lines and fuel lines and such shortly. I'd like to find somebody that would see if my ECU would make their 7 run. I know a few 7 owners in my area but they are mostly stock.

 

you can take the covers off of both sides of the ecu and look for any malfunctions, burn marks, cracks, etc.

if there is anything wrong with it, you should be able to see it on the motherboard.

other than that, you are going to have to check everything under the hood either by swapping out parts or testing the elctricals.

mass air flow meter, boost/pressure sensor, omp, coils (leading and trailing), fuel pressure, fuel filter, plugs and wires, cas, tps, vacuum leaks anywhere, o2 sensor, solenoid resistor, main relay, fuel pump relay under the dash, and all of your fuses.

 

OK, I did what you suggested but it didn't make a difference.