Engine Wiring Harness Diagrams - Series II SC

Anybody have a detailed wiring schematic for the engine wiring harness for our cars? I plan on yanking the engine out of the wreck and frankensteining it into a Fiero.

the haynes manual is pretty acurate so far for grand prix's (does not include supercharged engines) for the most part.

I've got the '99 service manual, it should be pretty close. Let me know exactly what you are looking for and I'll see what I can do.

Well i installed 1.84 roller rockers today, all went well, but my life would not be complete if something did not go to hell. While moving the wire harness around to remove the rear valve cover something must have been moved too far because when i cranked the car it stumbled and died. I spent the rest of the night diagnosing the situation and i found my +5v signal wire for the MAF has broken somewhere in the wire harness. therefor I have no MAF right now. The car runs pretty well on the VE tune i have, but i'd like to get my MAF back.
What i need is a 1996 FSM wire schematics for the wire harness showing which wires go to what and the color codes. I believe it is a solid yellow wire that i need to repair, but i dont know if there are more than 1 of that color. I'd hate to cut the wrong one.
I believe it is broken somewhere close to where it plugs into the firewall, but i'm not sure exactly where. How does that box come off the firewall? looks like 4 clips and a bolt?
If all else fails i'm just going to do a full VE tune and forget the LQ4.

Side vent: Yesterday i was trying to help my roommate who was having a rough idle problem. The place he took it to recommended a top end clean. So i went out and got some seafoam to do it myself. We ran the SF and the car was running like shit. i figured i fouled the plugs b/c they were nasty. Car still ran bad with new plugs, I figured it wasthe ICM or coil pack (ecotec motor btw). he didnt want me to just guess at the problem so he took it to the dealer and they charged him $300 to fix the ICM.
Then between last week with the injector clip and coil pack, then this week with the MAF wire and the MAP connector breaking i'm really starting to think i'm a magnet for breaking cars.
oh, and i'm doing rockers on Devin's car tomorrow, tie rods on a friends accord next tuseday and fixing my neighbors F150 sunday. hope my luck changes quick!

Matthew

Here's the MAF wiring diagram, hope its the one you need. If not let me know and ill try to find a different one.

do you have a map for the main chunk of wires in the engine harness? i know i need to replace the yellow signal wire, but again i'm not sure if that is the only solid yellow wire in the harness.

Mr.Riviera wrote:

do you have a map for the main chunk of wires in the engine harness? i know i need to replace the yellow signal wire, but again i'm not sure if that is the only solid yellow wire in the harness.

I dont think you will find that diagram. It would be huge and extremely complicated. If all else fails, just run a jumper wire from your MAF to your PCM.

i know it's broke somewhere between the MAF and where the harness connects to the firewall, so i'm going to run a jumper from those points.
I think i'm going to wait till next week so i dont have any more problems with it. it's running fine with no MAF (thank God i did a VE tune!, and thanks Devin).
I appreciate the help and i'll probably post up again when i start tearing into the harness.

Mr.Riviera wrote:

i know it's broke somewhere between the MAF and where the harness connects to the firewall, so i'm going to run a jumper from those points.
I think i'm going to wait till next week so i dont have any more problems with it. it's running fine with no MAF (thank God i did a VE tune!, and thanks Devin).
I appreciate the help and i'll probably post up again when i start tearing into the harness.

from recent experience...tearing into that harness = nightmare!

I'm actually battling this same problem right now, p0102. I have a 0 Hz MAF reading, and i thought it was a vacuum leak (is 39" Hg at idle too low?). When i start the car with the code active, it idles fine but returns the 0 Hz reading, but when i clear it and start it up again it chokes and hiccups and sounds like its purging all kinds of air and then dies. So after measuring, it seems like I'm not getting any voltage at the pink wire at the MAF sensor which is the power wire (yellow is the PCM signal wire). I do have continuity between the sensor and the firewall connector at the pink wire pins marked "Ignition Fuse Output". There are two of these identical pink pins side by side, and i have continuity between them and the MAF sensor, but i only get a battery voltage readout from one of them. Is it just a coincidence that continuity exists between the MAF and these pins, or do they contribute to the powering to the sensor? And to answer your question Matt, you just have to loosen the center bolt and the cover will come off. I have the chart and table for the connector and I will try to post them later. Did you test voltage at the MAF?

Continuity between adjacent wires can mean a short to ground or shorted together.

sorry for the half ass screen shots but the SVG viewer for mitchell wont let you save the image.
here is a zoomed out view of the whole diagram, the MAF is double underlined in the bottom right.


here you can see the MAF, all 3 wires, and where its grounded (could be your issue).


here is the routing of your pink wire, i have added black arrows to it. if you cant see it, it is PIN 65


here is the rest of the routing for the pink wire, this is the part that went up off screen on the last picture. i have circled the MAF fuse for you, this would also be something i check before tearing into the harness.


here is the routing for the also mentioned yellow wire, again i have added arrows. and again if you are unable to see it, it is PIN 54


here is the last screenshot i took showing what the big block is in the left of every pic, its the PCM.



hope this is of some help i can get some better zoomed in shots if this doesnt work for you, sorry again for the shitty screenshots. if you want PM me and ill give you my mitchell username and password.

PM sent

So i found a break in the yellow wire the c101 connector on the firewall and repaired it, and got continuity between it and the MAF sensor. After starting it up the p0102 MAF code was still there. I know there's a second yellow wire input on the connector at a different pin that also lacked continuity, but didnt have any visible breaks. Why are there two separate yellow wire inputs to this connnector when on the above wiring diagram it only shows one yellow wire from the MAF to PCM?

I guess you can't trust everything you read.
Maybe the FSM will help with a better wiring diagram, although I've found Mitchell diagrams to be very helpful in the past.
Who Knows??? You can always try a local Large Library for manuals.

I'm not trying to discredit that wiring diagram but I just dont get how the one yellow PCM signal wire from the MAF splits into two at that connector (or why it does). Either way I guess that wire is the next step since I'm pretty sure it had continuity issues as well. For anyone who might want to know the pins are A6 & E6.

L67 wrote:

I'm not trying to discredit that wiring diagram but I just dont get how the one yellow PCM signal wire from the MAF splits into two at that connector (or why it does). Either way I guess that wire is the next step since I'm pretty sure it had continuity issues as well. For anyone who might want to know the pins are A6 & E6.

Are you sure you don't mean A6 & F6?

I'm looking at the GM electronic service manual, and C101 has:
-Yellow MAF signal at A6
-Gray EGR output at E6, and
-Yellow VSS signal at F6

The only other Yellow is at H1, for the CTS signal... (Coolant Temp Sensor)


Hope this helps,
Mark

also, have you cleared the code? The SES light may not go off just because the sensor is working now.
Matt, it sounds like you are having the exact same problem as me with that yellow signal wire. With the scanner hooked up did it show a reading from the MAF after you repaired the wire? (hz or inHg)

I have +12 for the pink wire btw.

Mr.Riviera wrote:

also, have you cleared the code? The SES light may not go off just because the sensor is working now.
Matt, it sounds like you are having the exact same problem as me with that yellow signal wire. With the scanner hooked up did it show a reading from the MAF after you repaired the wire? (hz or inHg)

I have +12 for the pink wire btw.

I cleared it and it came right back, my MAF is still reading 0 Hz. My pink wire does have voltage now, i think it was just a bad ground when i was testing it. And to Eldo, sorry if I mixed up the second pin number, I was trying to go off of memory since I'm back at school now. Although both of mine are labeled MAF signal wire (not VSS like you said) in the FSM, so maybe the 96 is different. I repaired the one at A6, which was apparently damaged while repairing the wire at A7 (cam sensor) last week. So I'm assuming there is something up with that second yellow wire since I can't really see my MAF sensor failing under these coincidental circumstances.

L67 wrote:

And to Eldo, sorry if I mixed up the second pin number, I was trying to go off of memory since I'm back at school now. Although both of mine are labeled MAF signal wire (not VSS like you said) in the FSM, so maybe the 96 is different. I repaired the one at A6, which was apparently damaged while repairing the wire at A7 (cam sensor) last week. So I'm assuming there is something up with that second yellow wire since I can't really see my MAF sensor failing under these coincidental circumstances.

Well, there could be a difference between years, like in the oil level sensors. '96 S/C is a Series II, right?

For what it's worth, A7 is also the Cam Sensor on my chart, but there is only one MAF sensor terminal.

Eldo wrote:

L67 wrote:

And to Eldo, sorry if I mixed up the second pin number, I was trying to go off of memory since I'm back at school now. Although both of mine are labeled MAF signal wire (not VSS like you said) in the FSM, so maybe the 96 is different. I repaired the one at A6, which was apparently damaged while repairing the wire at A7 (cam sensor) last week. So I'm assuming there is something up with that second yellow wire since I can't really see my MAF sensor failing under these coincidental circumstances.

Well, there could be a difference between years, like in the oil level sensors. '96 S/C is a Series II, right?

For what it's worth, A7 is also the Cam Sensor on my chart, but there is only one MAF sensor terminal.

Correct, '96 is a Series II SC. Still don't see why one yellow wire would need to split into two

so you tested a +5v (key on)from the yellow wire at the plug for the MAF?

Mr.Riviera wrote:

so you tested a +5v (key on)from the yellow wire at the plug for the MAF?

I have not done that yet since I wasted most of my time on the pink wire. I'll try that next since thats in the troubleshooting table. Did you check for continuity at the connector? Or are you getting 0v?

i get 0v at the yellow wire, but i know its a broken wire b/c if i squeeze the harness and move it certain ways i will get +5v.

Mr.Riviera wrote:

i get 0v at the yellow wire, but i know its a broken wire b/c if i squeeze the harness and move it certain ways i will get +5v.

Thats what i thought happened to mine but even after i fixed it its still not working. Hopefully its near the connector like mine was, and not buried somewhere in the loom.