2G Weird electrical issues, please help!

[88BB8B]

Hello everybody. since my last post a new problem has occurred. I am struggling to figure out what the heck is going on with my car! At first I thought it might have been my AEM infinity dumping out on me, but after plugging in the stock ECU and seeing similar problems I think it is an electrical issue in my car. It started off as my ECU (infinity) cutting out while I was driving. I would have to disconnect the batter and reconnect it to get power back to the ECU. Now the car wont even start. I will have my laptop plugged into my infinity display on, and when I go to crank the car, the display immediately shuts off (the ECU loses power). on top of that, my ABS is making a weird clicking noise when the accessories is on, and the ABS dash light flick with the click, I think the issues may be related. I also have some sort of main power relay (I'm not sure if it is stock I didn't do the wiring on my car) and normally when the car was ooerating as usual, I would hear this relay rapidly click after I took the key out, like its powering down, it seems to be only doing this sometimes now. When the ECU starts up and works properly with the accessories switch on, the relay will click and power down. When the ECU refuses to start up as normal, the relay doesnt click.

This is just my best description of an issue which has a lot of symptoms that intermittently appear at different times, but it seems like something isn't getting power consistenly when it needs to. I don't know much about how the electrics are setup on this car, and am so lost trying to troubleshoot this. I have a multimeter, tell me where to poke It! I would appreciate anybody's help enormously!

 

[88BB8B]

Update: When I have the accessories on, and the ECU is on, if I press the trottle pedal all the way, power to the ECU gets cut. I disconnected the TPS and it still does it. is going on?

 

[ThunderChild]

That's whacked...start hunting for a short somewhere in the wiring, mouse chew marks or something that melted. I'm betting you'll find roasted wires in the dash somewhere.

 

[dustyboner]

make sure your AEM is running the latest firmware. If your not try updating the firmware and see if it fixes the problem.

Are you running all the stock sensors?

the main relay and fuel pump relay are in a single unit on the 95. It should look like:

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[Mello]

Another thing you should check to make sure it's working okay is the ignition switch. When they are starting to fail or have failed you can get weird problems like you're experiencing too. Attached is the 1997-1999 FSM excerpt for the ignition switch. I don't have the 1995-1996 in pdf but this still may help.

 

[88BB8B]

I have already tried updating the EMS it didn"t seem to help. I noticed sometimes when I turn the key to accessories that fuel pump main relay combo clicks very rapidly, sometimes it wont stop until I turn the key off, and also, when I got to crank and the ECU shuts off, if I have my hand on that relay I can feel it click off, but I'm not sure if its an issue with the relay or power supply to the relay, you think it would be worth swapping out?

 

[Philip Bidwell]

These relays are the hardest to find right now. I'm in the middle of searching for this and have reached the conclusion that they will only be found in bone yards or I have to figure out what it takes to fashion my own version. Does anyone have a lead on one of these?

 

[88BB8B]

https://millerimportparts.com/95-96-Eclipse-Talon-Turbo-4g63-MPI-Relay-Fuel-Pump-2g-P2519939.aspx

 

[DogWhistle]

,,, an issue which has a lot of symptoms that intermittently appear at different times, but it seems like something isn't getting power consistenly when it needs to.

You could be chasing gremlins for a long time. Start with the basics. When weird symptoms appear and disappear, many times it is a voltage fluctuation issue. Pull the battery and have it LOAD tested. Better yet, buy a new one and charge it completely. Have your alternator checked too.

Without consistent performance from the battery and alternator, every time you turn the key, the car's circuits are going to try to work with whatever voltage they can get, and the results aren't pretty.

 

[AWD-Tony]

+1. Check battery and charging first. Make sure they’re up to par along with connections and grounds. Another simple check - wiggle the ignition key and see if this sets off any of your symptoms.

 

[88BB8B]

Thanks for the advice. I'll definitely do those things. I think that the batter it probably okay though. It charges at about 13.7 V if I recall correctly, and it cranks the car very strong. The issue also still happens when I have a charger on the battery, so I think its probably pretty safe to say it isnt the battery, but I have others laying around that I could give a shot.
I went ahead an ordered the relay because it was only $25, but I think it must be the relay, or the ignition switch. I also noticed that my fuel pump doesn't run when I crank the car. Is it supposed to? It primes normally, but doesnt run while cranking.

Are there any other potential culprits you guys could think of?

 

[88BB8B]

If I may post here again I am still needing some help with this. So since last posting I got a new battery, and it definitely cranks good, 690 CCA, but this issue still persists. I thought I had narrowed down the issue to the ignition switch because it appeared that the voltage was dropping across it, so I replaced it and it doesn't seem to have helped. I thought maybe the stock ignition switch just wasn't compatible with the infinity so I bypassed it completely by wiring a toggle switch straight off the battery to the ECU ignition switch power supply, still didn't help. It appears that the voltage through the toggle switch is 12.5v when the ignition is off and the toggle switch is off, but when I turn the ignition to accessories the voltage across the toggle switch drops a little, and when I turn on the toggle switch it drops even more. I've been pointed in the direction of "probably too much resistance in the ignition system somewhere" and I think that makes sense (the more current pulled the more the voltage drops) so I should probably start at the battery and follow it back until I find the source of the voltage drop right? I started checking from the battery back with my multimeter, and I kept getting battery voltage of about 12.5V between the battery ground (which is grounded to my transmission) as I followed the wire to my toggle switch back I kept getting 12.5V that's when I realized I had been measuring the voltage through that toggle switch to chassis ground, and for some reason there is a 2V difference between my transmission and my chassis. I don't know what this means or how to go about fixing it. You guys think there is some weird wiring making my chassis an ineffective ground? Should I just ground my ECU to the engine/transmission? Thank you all very much in advance for any help.

 

[o0GuitarKid0o]

I'd check all your ground locations to start and clean them up.
Have you checked for voltage drop from your battery to the battery clamps?
I had something similar happen with my old battery cables being squished so bad that they barely made a connection.
Caused a whole bunch of issues with the car dieing and lights coming on ect..

Running marine clamps for the last 3ish years no issues anymore.

You should be able to twist the battery clamps and have them not move at all.
Think my bad clamps dropped voltage down to 10v while the battery was at 12.6.

My guess is your ECU is shutting off from lack of voltage.
I may of missed this but does the car crank over?

******Have you looked into your ECU for bad capacitors and the common blown sensor trace ? As both will cause a no start.
The ecu triggers the mpi relay and the mpi relay turns on the Ecu and fuel pump.

Have you tried grounding the fuel pump test connector at all to see if it is turning on?

Start with the easy stuff when your chasing electrical demons , I wouldn't start throwing parts at it as usually you end up spending more money that way. I Doubt your mpi relay is cooked.

The clicking I'd bet was caused by not enough voltage to keep the mpi relay closed.

You'd be surprised how easily a 2v voltage drop can make your car a nightmare.

 

[88BB8B]

I initially thought it was the MPI but I had a pare lying around and it didn't fix the issue. The car cracks and starts it was just acting strange as described above. I unblocked the ECU ground from the chassis and wired it to the negative battery terminal, so it is now grounded to the transmission. It seems to have worked, but I would like to dig and figure out what is causing the chassis to be such an ineffective ground.

I should clarify. When I have my ignition turned on, if I measure voltage at the battery and my negative problem is grounded to the engine block or transmission, then I get a good 12.5V when the engine is off. But if I measure with the chassis as my ground, then I get a poor 10.5V-11.0V I don't understand car electrics enough to know why this is happening though, I was told that there might be too much resistance in the ignition circuit, but then why does the transmission work as a good ground? Idk...