420A Welded coolant pipe, now no power to engine electrical

[Morris95talon]

I have an electrical problem that im stumped on.
Friend welding a patch to the coolant pipe and used battery as ground, battery WAS connected. Now i have No power to engine components. Interior components work fine. I manually tested each component and they work i double checked all fuses and did full relay test on f.p relay and pfi relay. Could my issue be a fried ecu or... What else?

 

[randman2011]

What car do you have? On a 2g it's really easy to pop the cover off of the metal ECU and check the power diode to see if it has sploded. What do you mean you "manually tested each component?" I would start with a multimeter and check for +12V everywhere that it's supposed to be. Starter solenoid, ECU, MAF, etc. The bolts that hold the larger 50A+ fuses in the fuse box.

 

[Morris95talon]

Sorry im horrible when it comes to proper terms. I have 95 eagle talon esi and i used voltage test and everything checked out good even direct wire test wad good.i took out the ecu but found no info on how to repair it. I am confident about fixing myself if i know the right way to diagnose it. Should i go ahead and open it and see if something blew?. Thank you for the Amazing help!

 

[95FullSend99]

Sorry im horrible when it comes to proper terms. I have 95 eagle talon esi and i used voltage test and everything checked out good even direct wire test wad good.i took out the ecu but found no info on how to repair it. I am confident about fixing myself if i know the right way to diagnose it. Should i go ahead and open it and see if something blew?. Thank you for the Amazing help!

Yes. Open the top of the ecu and take a look. The smell will be obvious. Burnt electronics. Take a look and a photo and post it here. Get into the electronic service manual and trace the path of power. Check for 12 volts along the path.
Assuming the 420a is wired similarly (i do not know), the initial path from battery through fuse box is simple. The ecu itself gets power from the mpi relay but it is also connected to the ignition circuit so there is a path there. The mpi relay gets power from the mpi fuseable link in the engine bay fuse box. Power for what is left in the ignition circuit comes from the engine bay fuse box ignition fuseable link. On a 2g 4g63 this is link number 4 and 6. The ecu also receives backup power on a 4g63 from at a fuse box under the hood. Fuse 11. This backup power is how the ecu maintains its ram. Pin 80 for a 2g 4g63 is where that pinout is and it should be receiving power no matter what as long as the battery is connected.

The exact path of power is when the ignition switch provides 12v to the ecu it ground to the mpi relay switching said relay providing power back to the ecu and through to various sensors in your engine bay. Your car then will be ready to start.

Most of this information i pulled from an old bookmarked thread written by "steve" in 2006. I will give him the credit where credit is due.

And here is the link to the thread in which Steve explains all this. I probably should have just supplied the link and not typed it out but whatever. Good luck on your electrical diagnosis. Post number 8 is where he talks about ecu power.
https://www.dsmtuners.com/threads/w...er on pin 80 (red with,ECU to power itself up.

 

[motomattx]

The non turbo car is completely different in how it works, also the ecu cannot be opened up on the non turbo.

 

[95FullSend99]

The non turbo car is completely different in how it works, also the ecu cannot be opened up on the non turbo.

Thank you for the clarification. I wasn't sure but information all the more.

 

[Morris95talon]

Thank you everyone for there quick replys. And thank you for the info. I did pull the ecu lid off and correct its layered in red goo. I have reason to believe this problem is in the ecu. I will update in the morning.

 

[Morris95talon]

So i installed a new( reman) ECU. Now i have all lights back on in dash for engine and everything you can hear turn on fuel pump etc. But right when i turn the key..... nothing.. I dont get it...
Now i do hear a couple of clicks from relays under the hood and in the cab.

Found that the starter relay under the radio might be bad. I used a test light and all wires get power except 1 which is black and yellow the thicker one and that is with ignition on

 

[Morris95talon]

Ok Team! Here we go... Problem semi solved!
Good news is that the car fired right up with new ECM. But not right away. I will list what i did that caused problem and errors i made.

-Welded part on coolant pipe with battery connected-
SMH i know... Trust me i kicked myself when i noticed. But it was to late.

1. Car dont start so i jumped on youtube and dsm and grabbed my scanner. Scanner couldn't connect.

2. Tried what i saw in videos and read. Bypass starter relay by Using jump wire. Car cranked no start

3.Connected black and red to skinny black and yellow. Nothing. No crank
I think i tried skinny BLACK and YELLOW stripe wire To RED and BLACK stripe wire or it was RED and BLACK to thick BLACK and YELLOW stripe. But now nothing.. No crank
4. Went back to the beginning with the basics. Check fuses w/led test light. Found a couple of fuses blown. Interior lights
Still no start
5. Noticed no check engine light or oil or temp or any engine light except door and brake.
6. Tested each engine part individual with volt meter and battery..starter f.p and everything worked.
7. Bought new ECM. Now Engine light and everything back on but..
Still no start
8. Tested ignition wires to see if anything grounded or no power etc. Everything checked out good
9. ✔ starter relay with volt meter and battery
10. ✔ mpi and f.p relay with volt meter and battery
Everything good.
Still no Start.
11. Lets try Jump wire. Where starter relay goes. Under the radio again.....
Black and red wire To skinny Black and Yellow
Nothing GrRrRRRR!!!!!!
OK..... Lets TRY
BLACK AND RED TO FAT BLACK AND YELLOW......
VROOOOM!!!!!
I think it might be starter relay but.
Not sure.
Under the dash there is a white fuse plate and there are 2- 10amp fuses and a relay. Top fuse reads power and bottom fuse reads ground. The 2 wires that come from the ground fuse i believe is black and red. Goes to the relay In the picture i post you can see the 4 wires
-Top left BLACK and RED stripe
-Bottom left Thick BLACK and YELLOW stripe
-Top right Skinny BLACK and YELLOW stripe
-Bottom Right RED and BLACK stripe

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I will update later about the starter relay when i replace it. So far it started. Hope this helps someone.
Thank you again Everyone

 

[Steve010]

I have an electrical problem that im stumped on.
Friend welding a patch to the coolant pipe and used battery as ground, battery WAS connected. Now i have No power to engine components.

Always remove the ecu and the alternator before doing any welding.

 

[Morris95talon]

Now guess what.... Its in limp mode check engine and code C0305??
Thank you

And it only runs with jump wire with starter relay removed. Could this be bad ground..?

 

[Morris95talon]

Ok so now i have the check engine light on trans in limp mode and the code is C0305?

Any ideas?

 

[dustyboner]

is your car an automatic or manual? does it have the factory alarm?

as far as i know, there is no "C" codes, only "P" codes. (on your car)

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[Morris95talon]

Thanks it is an automatic and yes as far as i know the factory alarm. I just have key, no key fob.

 

[dustyboner]

compared to 96+ cars, the 95s are setup way different as far as the PCM and TCM wiring. And since i don't have a 95 electrical manual, i had to go off the 96 manual.
hopefully the theft alarm and starter relay wiring is the same.

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if the theft alarm starter relay is good, maybe its the TCM

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you might wanna check for codes by using the "key dance" method. I know your probably like what the FaQ is that, so check this LINK

here are the '95 PCM (powertrain control module) pinouts in case you need them.

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[Morris95talon]

Perfect! Thank you!! This does help and yea i noticed the check engine doing the pause light dance but. Upon digging deeper i found a short. The wire is white, not alternator wire but it leads to the fuesable link from the battery. I will post pics in the morning. Im almost Almost there!
So just an update car will start with jump wire in starter relay location but with relay connected i get nothing but clicking from relays and sunroof and reverse lights do not work. I tested relay with power and ohm test and it is working.
All help appreciated

 

[Jk's97DSM]

Your friend used the ground side at the battery to weld the water pipe?

 

[Morris95talon]

yea smh...

 

[Morris95talon]

I so update time! I found my short in when i pulled my door lock fuse.. Voltage no longer draining battery. So. My reverse lights, sun roof still doesnt work but fuses are good..

Where can i find a TCM for My 1995 Eagle Talon ESI auto.
i found 1at oreillys but the listing says doesnt fit my vehicle.
I believe this is causing the C0305 code and my transmissions Limp Mode

 

[dustyboner]

https://www.ebay.com/itm/1995-Mitsu...552441?hash=item1a8b7fb639:g:BvUAAOSwkEFd8Asa

 

[92AWDHX40]

performance partout, ask for john, or nathan.

 

[Morris95talon]

Perfect thanks everyone for the fast reply. Got one on the way!

 

[Morris95talon]

Ok everyone new update..

New TCM seems to be shifting all gears. Only got up to 40 and down shifts felt good.
But something still is wrong. CHECK ENGINE light still on right at start with same code which says refer to owners manual C0305.
I noticed while sitting there with my door open my interior lights are not on so i tap the door switch and it flickers on and off and if i hold it in the right spot everything is on full but the min i let go it dims back down and light turn off and dash door light turns off. I thought new TCM would eliminate ✔ engine light and was hoping it would start with the relay in but it doesnt. I still need the byepass wire on the starter relay. I cant figure where or if there is a short. Besides the Door lock which i removed the fuse.

Any suggestions!?

 

[Morris95talon]

Question:
When removing starter relay and using a jump wire
Do i also or can i also.. jump the red and black wire and skinny black and yellow wire that go to that sensor which might be the neutral saftty or transaxle position sensor? Should i try it.

 

[dustyboner]

try this.
with the relay plugged in to the harness, take the skinny black/yellow wire and ground it to the chassis. then try to start the car with the key. if its a problem with the neutral safety or transaxle position sensor or what ever its called, it should start with that wire connected to ground.