The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support STM Tuned
Please Support Morrison Fabrication

2G 2g no start/no ECU power

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

TimF

10+ Year Contributor
823
5
Mar 14, 2011
Aurora, Illinois
Few weeks back my 2g just lost power to the ecu. It initially started fine that day. Drove it with ecmlink streaming. Got back home and turned it off to move another car (keys where on the same key ring) came back to it no more than 5 min later and the car just cranked. The CEL does not come on when I turn the key. Ecmlink would no longer connect, and neither could my ob2 reader. Tach doesn't read while cranking and I cant here the fuel pump (Walbro 255) turn on. Everything else works electrical wise. I tired swapping another ecu still won't power up. Checked the fuses they are all fine. When I checked the two relays behind the radio the that has black wires going into it does not click, while the one with red does. If I switch the plugs it still won't click so both relays are working (I also tested them outside of the car directly to a power course they are both clicking) what else should I look for
 

Attachments

  • 20170101_163017.jpg
    20170101_163017.jpg
    230.2 KB · Views: 187
Any body ? Car is still down. Tried a new power transistor and no luck
 
Tim,

Start working with your voltmeter to track down why your ECU isn't getting powered up.
As a first step you can verify that you're not getting 12v at the ECU pins on pins 12 and 25 when the ignition switch is on. Then check to see if you get 12v at pin 80. If the ECU doesn't get the unswitched backup power it can't switch the MPI relay on in response to seeing the ignition turn on so you'll never get power to 12 and 25.

If you have power to pin 80 you start looking to see if the MPI relay has power and checking that the ECU gets the signal from the ignition on pin 82.

Swapping parts isn't going to fix this and can make things worse. Find a warm place and prepare to spend some time upside down on your back.
 
Tim,

Start working with your voltmeter to track down why your ECU isn't getting powered up.
As a first step you can verify that you're not getting 12v at the ECU pins on pins 12 and 25 when the ignition switch is on. The check to see if you get 12v at pin 80. If the ECU doesn't get the unswitched backup power it can't switch the MPI relay on in response to seeing the ignition turn on so you'll never get power to 12 and 25.

If you have power to pin 80 you start looking to see if the MPI relay has power and checking that the ECU gets the signal from the ignition on pin 82.

Swapping parts isn't going to fix this and can make things worse. Find a warm place and prepare to spend some time upside down on your back.

So do I just keep ignition on. Touch positive lead to those pins and negative lead to the ground and see if I get 12v through the pin? Sorry I'm not good when it comes to electrical diagnosing
 
So do I just keep ignition on. Touch positive lead to those pins and negative lead to the ground and see if I get 12v through the pin? Sorry I'm not good when it comes to electrical diagnosing
I believe that's correct. Take the time to get good at this because electricity flows throughout these cars, and it's so valuable to understand electrical gremlins and testing of sensors etc.
 
No power at 12 and 25. 80 and 82 do have power
 
Went back and check the relays. They won't click when I Turner to ignition. I swore that one did before nm own neither of them are. I checked and they are both getting power. Would I be able to just bypass the relay temporarily to see if that is the issue.
 
You could check to see if the mpi relay is good and I think the link I posted earlier is a good source for that or a Haynes manual. Also, Check your ecu to see if maybe you have a burnt driver in the there.
 
Last edited:
I have had my ecu open it looks fine.and I tried another one to and same issue.
 
We got new relays and what do ya know. So I'm just curious why do the relays work when I pulled them out and tested them (first thing I did) but didn't work in the car
 
Getting somewhere, good.

Next step is to check the wire that the ECU uses to activate the MPI relay. It's the one with the two red wires with black stripes. (outer on in your picture)

When the ignition switch is off 12v should still go to the MPI relay on those two wires. You should also see 12v on the blue with green stripe at the relay and at ECU pin 38 and nothing on the large red wire at the relay.

When the ECU sees the ignition switch turn on it will pull pin 38 to ground causing current to flow in the relay coil and the contacts to connect the power from relay pin 3 to relay pin 1 (the large red wire) feeding 12v to the ECU pins 12 and 15 along with the rest of the MPI circuit.

Assuming you have power to MPI relay pins 3 and 4, grounding pin 2 (the blue w/ green) to the chassis should turn on the MPI power and if the ECU works you'll see the normal CEL and boost gauge activity.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top