I bought an '86 with a 3800sc swap. It has been a riot to drive, except for a few wiring bugs. I bought another harness to re-wire it.

the patient



I opened the hood to find this



and this



It seems all the cars power runs through this 60 amp fuse next to the driver's ass. There was also a switch that turns the ecu on and off. :/



Under the console the stock ecu was gone and the wires were cut off.



On a side note, the exhaust was plumbed over the shift cables and in front of the intake.




So, I went to the junkyard today and brought home a wiring harness, exhaust crossover, and a pair of those heater hose barb thingies. Mine leaked, so I took them to work for new o-rings and lost them. Cost- $35.

Tomorrow I'll be sitting in the break room at work studying 3800 wiring and figuring how to make the gauges and everything work.

Why would they paint the supercharger the cover it with that mess ! That is pretty close to the one I am Re-doing right now, all i can say is it did run, how, i dont know.

Shoot me an Email if you need a copy of my wiring spreadsheet.

This is what happens when someone who has no idea what they are doing attempt to wire a car. Someone with no clue how to do it right and only want to make it run.

The second part of this is to wonder how much of it is working properly. I can't imagine that the PCM was doing anything but working in limp mode. Most likely wasn't programmed.

The po told me that he had all the wires wrapped and routed neatly until he changed intake gaskets. After that it wouldn't run so he unwrapped it all trying to find the problem. I bought it last Friday anddidnt have much of a problem getting it to start. The only gauge that works is the fuel gauge.

The issues I have had so far are that the battery wasn't charging. I ended up on the side of the road troubleshooting, and found that there was no plug for the battery that I could find. So with the help of my phone and the forum I was able to jimmyrig a wire to get the alternator to charge. The next issue was when the motor died out of the blue. I pushed it into a parking lot and found a circuit breaker that was way too close to a ground and looked like it had shorted a few times. I also going an unknown black wire that went to the passenger compartment. Fortunately I guessed right when I thought it might go to the switch that runs the ecm.

if i sqint my i eyes it looks like the chicken parm/ spagetti my wife made last night. it might even taste better. it probably isn't as bad as it looks.

quote The po told me that he had all the wires wrapped and routed neatly until he changed intake gaskets.

Wrapped in saran wrap?

[This message has been edited by phonedawgz (edited 05-05-2011).]

If you look closely at the (partiallly covered) name on the battery it self documents this mess...

quote Originally posted by tkemo596: If you look closely at the (partiallly covered) name on the battery it self documents this mess...

LMAO !! too funny ! nice catch !

If it were me id just buy a harness from a member here, and be done with it. However, I heard it not all tha hard just intimidating.

C500 is next to the battery, and c203 is in/under the console? There's a lot of reference to them, not much mention of where they are.

Yes. but you have to wonder how molested they are now. All the wiring diagrams are based on stock C500 and C203

I did rewire on mine a few years back. This is what I started with:


and made it look like this:



I've since relocated the fill for the intercooler to where the stock intake sits replaced the covers on the blower with engraved custom made covers and cleaned it up a little more.

Stick with it, the results are worth the effort put into it.

[This message has been edited by topcat (edited 05-05-2011).]

quote Originally posted by topcat: I did rewire on mine a few years back. This is what I started with: and made it look like this: I've since relocated the fill for the intercooler to where the stock intake sits replaced the covers on the blower with engraved custom made covers and cleaned it up a little more. Stick with it, the results are worth the effort put into it.

That looks great! GJ

Well, I have had TWO happy moments now. First when my 3800sc swap fired up for the first time after looking disgustingly at the rats nest under my hood and secondly, after seeing this, realized there is no rats nest under my hood.

Edit: You need some longer fuel lines and heater hose and route them somewhere like the passenger side frame rail and LOSE THAT 20lb I BEAM.

Steve

[This message has been edited by JumpStart (edited 05-05-2011).]

That wiring job looks like it was done by a half ass mechanic. If there is confusion here; you can run a 3800 by adding just 6 wires to its dedicated harness. All you've got to do is feed battery power, ground, ignition pwr, wire the cooling fan in and do a bit to insure the fuel pump feed though is complete. Thats the approach used on my 3800SC but with this simple wiring scheme you need to retain the GTP fuzebox/power center. If a car came to me the way yours shows I would just go wire by wire and build a new dedicated harness. The good news is that the car runs so it shouldn't be hard to correct.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Topcat- what transmission are you using? I've got a 4 speed in mine and am wondering if I can stick a stock exhaust crossover under the shift cables without melting them.

It shouldn't be hard to fix this mess, but with the scotch locks, wires that change color where they are spliced, and unprotected hot wire connections floating around I think it would be best to pull it out and start fresh.

That "dogbone" is definitely going to be replaced, possibly with two. I've been looking at the 3800 on my garage floor to see where I could bolt on a mount. Plus the spare motor will help in figuring out what and where each plug is.

https://www.fiero.nl/forum/Forum2/HTML/115710.html
look down in thread for wire diagram

You do know you can copy the image location and then just post it in the thread right?

Find the address of just the image - for example
http://images.fieroforum.co.../complete_wiring.jpg

Then to put it in the post use

[img]https://images.fiero.nl/2011/complete_wiring.jpg[/img} But use a square bracket at the end.

[This message has been edited by phonedawgz (edited 05-06-2011).]

Someone said there is no "how to wire a 3800" thread, so I'll document what I'm doing.

The wire harness



I took it apart using a special tool Lisle 14900. I bought it for when I converted a Chevy TPI harness to run on a TBI computer. It's not really needed for the 3800 connectors, just a small screwdriver or a pick or a razor blade, something like that.



Here's the harness, all in pieces.



Somewhere here there are pics of the ecm connectors. The clear and blue covers pop off, then you gently pry back the little finger and pull the wire out. if the wire doesn't come out, push it in and try again.

I hung my na motor up on the hoist so I could see where each plug goes.



I got all the plugs in their respective places, except for 3. These two



and



I did find the red one on the SC motor, but I don't know what it is.



I also discovered that I have apparently 2 transmission plugs. I have no idea where the second one goes. And that little plug with 3 wires?

[This message has been edited by Tuna Helper (edited 05-06-2011).]

quote Originally posted by Tuna Helper: Topcat- what transmission are you using? I've got a 4 speed in mine and am wondering if I can stick a stock exhaust crossover under the shift cables without melting them.

I am using the four speed Muncie, but the slave bracket is modified to get the cables out of the way of the cross over.

The second "trans plug" is just a interconnect to the body harness of the donor car, you wont use it. Th little 3wire one if the wires are green, yellow, and black it is you coolant sensor, if yoour collant sensor isnt a 3pin sensor you have the wrong sensor. The one above with the red connector is the Evap purge i think, I never use it. The others I dont recognize as anything I use.

Thanks for the info. I kept the radiator from the donor and I'll check it to see if there is a sensor.

I bought some sticky labels so I can label each plug and where each wire goes in the ecm plugs.

Lets go through the plugs... (the great thing about them is that they are made to only go in one sensor.

These two are knock sensors. The dark blue one goes on the starter side, the light blue one goes to an extension wire on the trans side.



The alternator plug. I'm not sure where the orange wire goes, I think blue 36.



IAC (idle air control)



IAT (intake air temp)



EGR (exhaust gas recirculation)



MAF (mass air flow) I think, it goes on the top of the throttle body



MAP (manifold absolute pressure) and TPS (throttle position sensor)



Coil packs and some other things. I think this is also the cam sensor and a hall effect for the ignition. There is a pink wire here I don't know where it goes, I think it is switched 12 volts.



I think this is coolant temp. Someone tell me where the green wire goes, I don't see it anywhere.



I thought this was oil pressure but I don't see it in the PDF. Someone correct me.



I'll do the injector plugs in the morning, it's a little late for me to get into that tonight.

[This message has been edited by Tuna Helper (edited 05-06-2011).]

The MAP on a supercharged engine is different the the N/A one you have pictured.

The Coolant connector you show is a secondary connector, there shoould be a short pigtail connector that goes to that and the 3 pin connector you showed earlier. I connect them direct and get rid of the extra connection. The Green will go to c500 to feed your temp gauge.

If you are using a 98-02 PCM and alternator you only need the red wire to the PCM, the other is not neccesarry.

On your ICM connector the pink will go to c500 +12ignition coil connection, you will also need to add a pin to thhe one missing in your pic. That is pin E, should be white, it will run to c500 Tachometer feed.

You will use the oil pressure sender and connector from the Fiero, you only need to use the center pin, runs to the oil gauge.

quote Originally posted by Mike Gonzalez: The MAP on a supercharged engine is different the the N/A one you have pictured. The Coolant connector you show is a secondary connector, there shoould be a short pigtail connector that goes to that and the 3 pin connector you showed earlier. I connect them direct and get rid of the extra connection. The Green will go to c500 to feed your temp gauge. You will use the oil pressure sender and connector from the Fiero, you only need to use the center pin, runs to the oil gauge.

The sc map looks just like the map on a tbi or tpi motor, except it's probably at least a 2 or 3 bar map.

Yes, the coolant sensor has a short pigtail, so does the trans side knock sensor.

I don't have the stock oil pressure sender or connector. Autozone doesn't have them, neither does Advance Auto. Newgmparts.com has them, but they are $54.33.

[This message has been edited by Tuna Helper (edited 05-07-2011).]

quote Originally posted by Tuna Helper: Is there any chance you can get another pic to show that better? I really really don't want to drive without an air filter.

I am on the way out of town. But will try to get a few shots of it when I return.

Rock auto has the '88+ style connector for less than $20. Make sure you get the 3 wire plug. Look for electrical connector for an 88 and they will have a number of different ones there. Of course don't get the 1 or 2 wire plugs.

If all you are going to do is use the middle pin of your 3 pin oil pressure sender, just drill out the holes for the other two pins but leave the wires out. The holes are cast into the plastic connector but don't go all the way through. If you have some little rubber plugs to put in the back side of the holes you should, or just put some RTV in there.

If you run just the one pin of the 3 pin oil pressure sensor/switch, then that wire just runs to the oil pressure gauge wire on C500.

http://rockauto.com

quote Originally posted by Tuna Helper: The sc map looks just like the map on a tbi or tpi motor, except it's probably at least a 2 or 3 bar map. Yes, the coolant sensor has a short pigtail, so does the trans side knock sensor. I don't have the stock oil pressure sender or connector. Autozone doesn't have them, neither does Advance Auto. Newgmparts.com has them, but they are $54.33.

The SC MAP connector looks like the 1 bar MAP however the plastic prongs are 'keyed' with slots so you can't just use the plug from an older style NA MAP connector

quote The alternator plug. I'm not sure where the orange wire goes, I think blue 36.

Good luck getting that pin into the PCM connector.

[This message has been edited by phonedawgz (edited 05-07-2011).]

I've got that bowl of spaghetti off my motor and am ready to wire. First things first, the odd cylinders are on the right side of the motor when looking at the crankshaft? That's one thing I have trouble remembering, and I can't seem to find it.

Is there an egr on an SC motor?

[This message has been edited by Tuna Helper (edited 05-07-2011).]

#1 it the one closest to the snout of the crankshaft. On the 3800 it's on the front bank, fully to the left. (yes the 2.8 has it different) 1,3,5 are on the front bank (bank 1). 2,4,6 are on the rear bank (bank 2)



Yes the 3800 SC can have an EGR. Yours does not.

[This message has been edited by phonedawgz (edited 05-07-2011).]

Cool, that's what I was thinking.

+ 4 U

It runs, but it stumbles. It'll rev fine, but falls over when you gas it in gear. I wonder if there's something I need to add that I haven't got to yet.

I'm also not getting 12v from clear 61, so the alternator isn't charging. I'll have to find something 12v with the key on.

[This message has been edited by Tuna Helper (edited 05-08-2011).]

PCM programming.

It ran good before though. I did change 3 things, I added both knock sensors and haven't wired in the 02 yet. Supposedly this ecm was programmed by a guy in Texas.

[This message has been edited by Tuna Helper (edited 05-08-2011).]

Is the PCM programmed to know it is not hooked up to an automatic transmission? Did they have some weird wiring in there to simulate the automatic transmission? Can you scan the PCM?

I'm going to start by checking my ecm connectors against the pinouts, then if that doesn't fix it I may have to have Darth Fiero look at it.

Update: I went pin by pin on Ryan's pinout sheet and compared it against the notes I took on what pins I was using. I found that I had missed an ecm ground, so I added that and moved my red alternator wire from the ecm to pin k of the c203. That is shared with the MAF power. Just going back and forth in my driveway it runs like it did. I still have to package the ecm in the stock location and clean up the inside.

I learned that if I do it again I need to separate wires from sensors that don't go to the ecm. (MAF power, ICM power, etc.) And then only bundle things up when I am 100% finished. So far I am 95% happy with it, I will have to make a few changes in the future but I am no longer worried about electrical issues.