2g alternator pinout

[dwdsm]

Doing a wire tuck and almost finished but.... whoops I cut out the alternator relay and now have no idea on what my options are for wiring up the black/yellow wire and the red wire from the alternator plug. From what I have seen just the red is to 12v ign. and the black isn't needed because it's the dummy light. Any help would be great.

 

[gofer]

Hope this helps, if not I've got pages of wiring diagrams I'll look through for ya. Don't feel so bad cutting out your wiring to the alternator, a local guy removed his TPS wires from his harness thinking it was his EGR valve and then he RTV'd his TPS hole on the TB.

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[dwdsm]

got it thanks! It looks like I can leave out the black/yellow after all. I have a voltage gauge btw. I have a couple more goofs I may pm you about. I got everything to work tonite and when I went to put in the tune the ecu won't connect to link.. here we go again...ugh and to think I did it for the props of a wire tuck.

 

[dwdsm]

Do you have the pinout for the obd2 port? scratch that I found it but what is the differenct between a signal ground and a regular one?
---car-side-OBD2 ----
\ 1_____________8 /
.\9____________16/

Pin 01 - DIAG (ABS, ATX, Door locks)- Yellow
Pin 02 - OPEN
Pin 03 - OPEN
Pin 04 - Chassis GND - Black
Pin 05 - Signal GND - Black/white
Pin 06 - ATX transmission (this wire is present on my '97 MTX) - Yellow/orange
Pin 07 - ECU DATA (K Line) - Pink
Pin 08 - ABS (cars with AWD) - Yellow/red
Pin 09 - ETACS (chassis switches pulse output) - Black/blue
Pin 10 - OPEN
Pin 11 - OPEN
Pin 12 - SRS (airbag ECU) - Yellow/green
Pin 13 - CRUISE CONTROL ECU - Yellow/black
Pin 14 - MULTI DIAG (speed, convertible top, etc) - Yellow/white
Pin 15 - OPEN
Pin 16 - +12v constant from ETACS/BATT - Red/black

I have a feeling that there is a missing ground that I didn't bolt on somewhere.

 

[luv2rallye]

You must have the black/yellow connected to the alt's L terminal for proper alt operation. The other end must go to the charge lights blue wire and that light must be connected to B+ and working. The generator relay is only needed should the charge light bulb not work so you can leave it off.

Signal ground is a ground wire to the ECU for sensors only. Regular ground is for higher current devices (non-sensors). They are separate because higher current devices would cause a voltage drop in the ground wire giving a misleading sensor voltage differential. So the sensor ground must be a separate wire all the way to the ECU (where it is grounded inside) and must not touch any engine/body/chassis ground metal. Some people incorrectly connect the O2 regular ground to its signal ground and blow out their ECU internal signal ground foil path. Other people incorrectly connect a sensors signal ground to the engine/body/chassis and never figure out why the engine sometimes runs a little crappy no matter what they replace (and mechanics usually won't figure this out either).

 

[dwdsm]

hmm thanks.. do you know of any sensors that would have a signal ground over a regular one? I am willing to bet that I grounded some signal grounds to the frame. Is there a wire that represents a signal ground over a frame ground? ex. black with white stripe.. I'll also check to see if my mitsu book indicates this in the wire diagrams but i doubt it.

 

[gofer]

I'm not sure where the accessories wiring harness grounds are that runs through the dash and out the drivers side fenders since I've never pulled it. I have pulled my main engine harness though and there are (2) ground points, each ground point having (2) connectors that bolt to the chassis. One ground point is behind the ECU and bolts down to the chassis under the shifter cables, the other is on the firewall straight below the battery tray and bolts to the firewall.

A signal ground and a frame ground are essentially the same thing, and they are black wires not black/white. What wiring harness did you start cutting stuff out of and what makes you think you cut a ground somewhere?

 

[dwdsm]

I can't get the laptop to connect to the ecu to even try to get it to run. My obd2 reader won't connect either so it has to be a wiring problem. I'll post some pics so you understand.

 

[luv2rallye]

hmm thanks.. do you know of any sensors that would have a signal ground over a regular one? I am willing to bet that I grounded some signal grounds to the frame. Is there a wire that represents a signal ground over a frame ground? ex. black with white stripe.. I'll also check to see if my mitsu book indicates this in the wire diagrams but i doubt it.

I just looked it up and found out that the obd2 port signal ground is different than the sensor signal grounds. It connects directly to the body and so is a separate path to ground for obd2 port signals. Both obd2 port pins 4 and 5 should connect directly to the body ground. You should check this. Pin 16 should have +12v on it (goes through the 10A door lock fuse).

As far as sensor signal ground info:
On a 2g (but not 1g) ECU pin 92 (note: this pin is incorrectly labeled Ignition switch on some 2g ECU pinout diagrams) goes to the signal grounds of the following engine sensors: manifold diff pressure, engine coolant temp, front O2, rear O2, TPS, volume air flow, and fuel tank diff pressure. Pin 92 is grounded inside the ECU but all these sensors signal grounds must NOT be grounded anywhere but through pin 92 to avoid electrical noise and ground loops from affecting the sensors differential signals and to guarantee that the sensor's ground is at the exact same voltage potential as the ECU ground (which it might not be with large current flowing through any other ground). If you think you have a sensor signal ground incorrectly wired just unplug the ECU. No sensor signal ground should now have continuity to body ground (some high resistance maybe {going through the sensor itself and then other devices to ground} but not anywhere near zero ohms).
Sensor signal ground wire color is all black but then so are many other ground wires so you can't use wire color for identification (just use which devices have signal grounds from list above).

 

[gofer]

I can't get the laptop to connect to the ecu to even try to get it to run. My obd2 reader won't connect either so it has to be a wiring problem. I'll post some pics so you understand.

I understand, no pics are necessary... Heres a shot of your OBDII port with pin out info so you know where to test with a multimeter rather than using those text symbols like you did above.

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The ones you need to worry about are Pins 1, 5, 7, & 16.

Pin 1 is the diagnostic pin and when tested with a multimeter should read 5v or higher, if not something is grounding it and can cause connection problems.

Pin 5 CAN use a chassis ground point, test it with a multimeter.

Pin 7 is an ECU data line, you can test for continuity between it and the pink wire going to ECU connector on pin 62 on the B55 connector.

Pin 16 should show 12v on it at all times when tested against pin 5, if its grounded properly. If it doesn't show power the fuse could possibly be blown, this same fuse powers the key illumination ring and the lights on the bottom of your rear view mirror. Its in the fuse box under the hood in the lower left hand corner and clipped together with another fuse. If you need to you can use the red/blue wire going to ECU pin 80 on the B56 connector if you need to.

Heres an ECU pinout if you need one. 2g ECU Pinout

 

[dwdsm]

I just looked it up and found out that the obd2 port signal ground is different than the sensor signal grounds. It connects directly to the body and so is a separate path to ground for obd2 port signals. Both obd2 port pins 4 and 5 should connect directly to the body ground. You should check this. Pin 16 should have +12v on it (goes through the 10A door lock fuse).

As far as sensor signal ground info:
On a 2g (but not 1g) ECU pin 92 (note: this pin is incorrectly labeled Ignition switch on some 2g ECU pinout diagrams) goes to the signal grounds of the following engine sensors: manifold diff pressure, engine coolant temp, front O2, rear O2, TPS, volume air flow, and fuel tank diff pressure. Pin 92 is grounded inside the ECU but all these sensors signal grounds must NOT be grounded anywhere but through pin 92 to avoid electrical noise and ground loops from affecting the sensors differential signals and to guarantee that the sensor's ground is at the exact same voltage potential as the ECU ground (which it might not be with large current flowing through any other ground). If you think you have a sensor signal ground incorrectly wired just unplug the ECU. No sensor signal ground should now have continuity to body ground (some high resistance maybe {going through the sensor itself and then other devices to ground} but not anywhere near zero ohms).
Sensor signal ground wire color is all black but then so are many other ground wires so you can't use wire color for identification (just use which devices have signal grounds from list above).

Thank BOTH of you so much. By volume air flow it's just referencing the MAS correct? I'll go over it tonite, double check everything and update you on the poor wire tuck victim.

 

[gofer]

Volume Airfow Sensor is another term for the MAF, thats what the wiring diagrams refer to it as. You can look at the back of the sensors connector to find the black wire going into it, that will be the sensor ground wire. I'm not sure what your wiring harness looks like though, so for whatever reason you can't see the wires going into the back of the connector below is the pinout for the sensor grounds.

You'll put one end of your multimeter on Pin 92 of the ECU and the other to the following connector pins and test for continuity...

• Manifold Differential Pressure Sensor (MDP) - Pin 2
• Engine Coolant Temp Sensor (CTS) - Pin 2
• Front o2 - Pin 2
• Rear o2 - Pin 2
• Throttle Position Sensor - Pin 4
• Volume Airflow Sensor (MAF) - Pin 5

** I didn't see where the Fuel Tank Diff. Pressure Sensor was wired into Pin 92 sensor ground, maybe luv2rallye can help. **

This is more a question for luv2rallye since I'm not an electrical master like he is, I'm still learning too! Looking at the wiring diagrams it shows both the front and rear o2 sensors are connected to a chassis ground, this would give all the above sensors continuity to body ground as well wouldn't it? I'm a bit confused from your previous post when you said

"No sensor signal ground should now have continuity to body ground (some high resistance maybe {going through the sensor itself and then other devices to ground} but not anywhere near zero ohms)."

 

[luv2rallye]

** I didn't see where the Fuel Tank Diff. Pressure Sensor was wired into Pin 92 sensor ground, maybe luv2rallye can help. **

This is more a question for luv2rallye since I'm not an electrical master like he is, I'm still learning too! Looking at the wiring diagrams it shows both the front and rear o2 sensors are connected to a chassis ground, this would give all the above sensors continuity to body ground as well wouldn't it?

The Fuel Tank Diff. Pressure Sensor is in my list as one that has it's signal sensor ground going to ECU pin 92 (connector E-58 pin 2, to connector E-09 pin 8, to connector C-29 pin 6, to along with other stuff ECU pin 92). I'm looking at the '99 real factory Mitsu Eclipse diagrams. It looks like that sensor may only be on the 98 & 99 however - glad you brought that up.

No the heater return wire is connected to ground in the ECU (pins 54, 60) when it turns them on (and this is the high current path which should NOT be used for signal ground. The signal grounds (O2 black pin 2's) are a different wire connected to ECU pin 92. When people mistakenly connect the O2 heater return to it's signal ground they blow the ECU (signal ground foil path) due to the high current the heater uses.

 

[dwdsm]

OK well last night I went over a few connections and checked quite a few things.
-I found that I did ground the signal ground at one point but quickly and easily corrected that by clipping it out of the grounding bar I made.
-All the apropriate sensors ground to pin 92, with the exception of the fuel pump which I did not change. All the little things work just fine. Windows, gauges, headlights, etc.
-DSMlink connected and I went to load my map only to find that it now says it lost connection... ugh.. looked through some stuff and the tried again and this time the fuel pump went crazy... on... off... on off... then on for a really long time... then off. DSMLink connects and then disconnects the same everytime.
-My 2a fuse blew on my wideband right away.
-Also the starter won't turn like it doesn't have enough juice so I tried another battery.. no luck. I have no idea what I did??
Two questions:
-One, when tracing the grounds off pin 92 I notice that the factory has it grounded to the body not too far from the ECU. this is obviously factory so should I clip it?
-With everything acting so goofy where should I start?
I'm thinking of pulling the entire harness out again but first I'll have someone help me test the voltage drop when in start position and retrace some steps. Push comes to shove I'll make my own diagram for you guys to look at.

 

[gofer]

Pin 1 is the diagnostic pin and when tested with a multimeter should read 5v or higher, if not something is grounding it and can cause connection problems.

What did you find when you tested voltage on the above Pin from the OBD port?

It seems to me like you got alittle carried away and removed too much from your wiring harness doing the wire tuck. Does the fuel pump turn off and on all on its own while your connected in link or are you turning it on manually through dsmlink? If you aren't doing it manually through dsmlink this could be a good place to start checking your wiring since the fuel pump shouldn't see 12v until you try to start the car.

 

[luv2rallye]

-One, when tracing the grounds off pin 92 I notice that the factory has it grounded to the body not too far from the ECU. this is obviously factory so should I clip it?

The ECU itself must be chassis grounded so if that's the wire you're refering to leave it alone. The sensor signal grounds that go to pin 92 are chassis grounded inside the ECU and must be chassis grounded ONLY there. They should not be chassis grounded outside pin 92. If you unplug the ECU and check continuity on them to chassis ground, you will find if they are. Note that it's not like the engine won't run if they are improperly grounded - it may just run poorly or inconsistantly. So I'd say your problem is elsewhere - perhaps a normal ground that's missing or not making good connection.
Of course if you connected the O2 heater ground to it's signal ground and blew the ECU's internal signal ground path foil, that's a different story.
Did you check that the OBD2 port pins 4 & 5 connect to chassis ground and pin 16 has +12v?

 

[dwdsm]

What did you find when you tested voltage on the above Pin from the OBD port?

It seems to me like you got alittle carried away and removed too much from your wiring harness doing the wire tuck. Does the fuel pump turn off and on all on its own while your connected in link or are you turning it on manually through dsmlink? If you aren't doing it manually through dsmlink this could be a good place to start checking your wiring since the fuel pump shouldn't see 12v until you try to start the car.

Pin 1 had 7.8v
Pin 5 checked out
pin 7 checked out
pin 16 showed 12.6
I got alot carried away with the tuck. I pretty much cut out everything I wasn't using/didn't need. No a/c, oem o2 sensors (althought I was running my wideband only prior to the tuck), cruise control, rear wiper, washers, heater, etc. the fuel pump was going nuts when I was connected but did not turn it on or off at anytime. I have some sorting to do and hopefully I can fix this..

 

[dwdsm]

Ok well I'm narrowing down problems.
Starter is now working fine just the clutch switch, I tried another ECU to find that the fuel pump did the same thing. I tested voltage at the ecu and it's getting 8v at pins 12 and 25 is that normal?. Grounds (13 and 26) test well also. Do one of you have the entire fuel pump diagram? What sends the signal to the fuel pump relay? I also noticed that a few of the relays seem a bit warm. Not burn you hot but warm to the touch. Not sure if that's normal.

 

[gofer]

Do one of you have the entire fuel pump diagram? What sends the signal to the fuel pump relay? I also noticed that a few of the relays seem a bit warm. Not burn you hot but warm to the touch. Not sure if that's normal.

The fuel pump relay has (4) pins on the connector going to it...

• Pin 1 BLK/BLU wire goes to the fuel pump and the fuel pump gauge
• Pin 2 WHT/RED wire comes from the ECU B-53 connector Pin 8
• Pin 3 BLK/WHT wire comes from the ignition switch
• Pin 4 BLK/WHT wire comes from the igntion switch

Those relays should feel a bit warm, just not HOT to the touch.

 

[luv2rallye]

I tested voltage at the ecu and it's getting 8v at pins 12 and 25 is that normal?. Grounds (13 and 26) test well also. ... What sends the signal to the fuel pump relay?

ECU pins 12 & 25 must have +12v with key on or you will have major problems (it's ECU power). Pins 13 & 26 must have continuity (0 ohms) to chassis ground.
Note that the fuel pump only runs when CAS is spinning (engine cranking or running). It does not run with key on but engine not spinning.

 

[gofer]

I don't think its been mentioned but does your CEL illuminate for 5 seconds and the stock boost gauge needle move to the middle when you turn the key to the "ON" position?

The 12v power source comes through the MPI relay to the ECU via the 20A MOTOR fuse in the engine bay. I'd check that fuse for continuity with a multimeter, sometimes a visual check won't spot a open fuse so test it. Then test for continuity between where the fuse pushes into the fuse box to the connector on the MPI relay Pin 3 RED/BLK wire.

 

[dwdsm]

ECU pins 12 & 25 must have +12v with key on or you will have major problems (it's ECU power). Pins 13 & 26 must have continuity (0 ohms) to chassis ground.
Note that the fuel pump only runs when CAS is spinning (engine cranking or running). It does not run with key on but engine not spinning.

I checked it twice.. I wonder what would possible make it have only 8.7v at those pins?? I'll run more tests tomorrow and let you know.

 

[luv2rallye]

You have a partial short somewhere. First unplug the ECU to see if it's the culpret (if still have less than 12v on those harness pins or on the MFI relay output). If so, start unplugging all the other stuff on the MFI relay one at a time until you get 12v (so the last thing unplugged will then be the culpret).

What "Engine" fuse and MFI relay provide power to on a 2g turbo:

Here is the complete list of what the 20 amp “Engine” fuse (in the engine compartment) powers on a 2g turbo:

Battery positive goes to this “Engine” fuse which then goes via a red/black (red with black stripe) wire exclusively to the MFI relay (which is controlled by ECU). From the MFI relay it goes via a red wire to the following (not in this order):

ECU, injector resistors (and then injectors after these), front O2, rear O2, CPS (crankshaft position sensor), CAS (camshaft angle sensor), volume air flow sensor, idle air control motor, evap emission vent solenoid, turbo waste gate solenoid valve, fuel pressure solenoid valve, evap emission purge solenoid valve, egr solenoid valve.

 

[dwdsm]

ooohhh yeah... I got link to hook up and all seems to be working! I'll keep you updated. Thanks Guys! I'd buy you some drinks if you lived a little closer! I'm not out of the woods yet but getting closer! Now I can trouble shoot much eaiser! Does anyone have the dia. of the ignitor module? I noticed it got super hot with the key in the on position. I somewhat think it was just because I hadn't fastened it down well and I do believe it grounds through it's bolt holes.

 

[dwdsm]

I went to set up dsmlink and it did the same crazy fuel pump thing again. I'll get this thing with enough patience... I also keep blowing fuses on my wideband... here we go again.