ECU making noise
 

I drove to my parents yesterday to help work on my dads accord. While I was there I took the battery out of my svx (optima red top) and dropped it into my dads suburban (I had reason to believe that my dads truck had a bad alternator). The battery got hot. And I mean quickly. It got very warm and I removed it. Tested the battery, and it tested okay. Put it back in the SVX.

Went to start my car and didn't get anything from the starter. Lights came on okay. So I tried to jump the car. Nothing. Hearing a clicking from under the dash, i suspected the inhibitor relay. Replaced it with a new one. Now, the ECU is making noise. By noise, I mean clicking repeatedly and rapidly when the key is in the ON position. It goes away when I try to start the car, but comes back when the key relaxes to the ON position again. When the ECU is clicking I can hear something scrape against the case when I push on it gently. So, it's definately internal to the ECU. Also, the CEL flashes with the clicks...

Did I fry the thing? Is there some other explination someone could give me for whats going on?

Re: ECU making noise
 

you on ecutune? make sure the mem adapter is totally secure

Re: ECU making noise
 

No chip yet. Getting ready to do that next week. Then this happened. :lol:

Kind of hoping its my starter. This is really weird...

Re: ECU making noise
 

Okay, I replaced the starter, no difference.

I am getting a voltage drop to the starter, though. By the time the current reaches the starter, it is really low, like < 5 volts. Tried a different battery.

So far, I have replaced the inhibitor relay and the starter. Tried with a known good battery. Everything is coming on and seems to be working okay, but no crank...

How many things can there be down there? What about the 5 prong bosch relay that was being bypassed in the relay mod? Could it be the security system or something?

Any help would be greatly appreciated.

Re: ECU making noise
 

You mean "less than 3" volts, right?

Are you 100% sure the clicking is coming from the ECU? Not something else in that area?

Re: ECU making noise
 

HA. I was like, what the hell, ya that's what that symbol means. :confused:

Then I saw the heart. Didn't know it did that :lol:

I changed my post. The voltage went up slightly with the known good battery. Still this is strange.

Another recap. The starter is getting approx 4.0-4.5 volts at the remote wire. This may be as designed, I am not sure. Speculating that there is a relay internal to the solenoid housing that the remote wire engages, which allows the constant (12v) signal to engage the starter.

Ran a second ground to the starter, and jumped it straight from the battery. It clicked, but did not engage and did not crank the engine. I think they may have given me a bad starter. I will go trade it in tomorrow hopefully. Then try my diagnostics again.

A couple of noteworthy things here.

1) When I turn the key to the start position the dash clock dims. LAN mentioned this in a thread a while back, but I cannot quite figure out what direction I should go, since it seems he blamed the starter.

2) I am worried I may have damaged some internal circuitry when I put the optima back in.

These electrical problems get old fast...:(

Re: ECU making noise
 

Yep. I'm pretty sure it's supposed to get 12V though.

Yea, if you gave +12V to the tab on the starter, and the positive starter lead is bolted down, and the battery is good, then it should absolutely have turned over if the starter is good.

Re: ECU making noise
 

There is nothing inside the ECU that can make a noise. But I've had the rapid clicking on one of my cars when I damaged the ECU.

There's a relay, controlled by the ECU, that provides power to the ECU. Basically it allow the ECU to reboot itself if it's not happy. On my ECU, the RAM went faulty and it did the rapid clicking thing exactly as you described. Rebooting over and over.

I guess it's possible that same thing might happen if the ECU has insufficient voltage.

I think your best bet it to find out which relay is clicking and look it up on the wiring diagram.

Re: ECU making noise
 

Thanks for the info. It would have to be close to the ECU then, correct. Any further insight?

Re: ECU making noise
 

I would looking at the +12V wiring upstream of both the starter switch and the ECU, it's probably a problem with something that supplies the power for both that got fried.

Re: ECU making noise
 

That's what I am thinking. I am looking for the wiring diagrams right now but don't have a hard copy, and am having trouble locating them here.

Re: ECU making noise
 

I have the electrical wiring diagram here:

http://svx.northursalia.com/wiring/wiring.pdf

Re: ECU making noise
 

You, sir, are awesome :).

Re: ECU making noise
 

Battery was fried...12v, but only 10 amps. Much less than needed. Replaced the battery, and everything is better now.

Leave it to me to make things more complicated than they really are...:D

Re: ECU making noise
 

Yaaay, congrats. Thx for posting the solution, makes someone searching years later so happy.