Pennock's Fiero Forum
  Technical Discussion & Questions
  84 Failed ECM

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
84 Failed ECM by Javalin
Started on: 07-14-2014 11:10 AM
Replies: 2 (163 views)
Last post by: Javalin on 07-14-2014 04:41 PM
Javalin
Junior Member
Posts: 2
From: Mojave Desert, California
Registered: Jul 2014


Feedback score: N/A
Leave feedback

Rate this member

Report this Post07-14-2014 11:10 AM Click Here to See the Profile for JavalinSend a Private Message to JavalinEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hello Everyone,

This is my first post but I've read around a bit for the past week or so and the past days pretty intensely.

I have a project on my hands. I'll go through what I have done so far and what I've looked at. I've got an 84 SE 4 speed. When I brought it home the fuel pump wasn't running. Besides that the guy I got it from said that it was overheating because the fan relay or the fan motor wasn't running he wasn't sure which was bad. (I now know he had no idea what he was talking about)

I got the fuel pump changed out. And if I put starting fluid on the throttle body I can start the car but it runs at VERY high idle. Around 2500.

When I turn the key on the fuel pump relay doesn't click on. I tested the relay and when the green/white wire is supplied with 12V the fuel pump runs. I tested at the ECM and with the key on the ECM doesn't send 12V out.

I also am not getting any spray from the TBI injector, is there a cold start on the 84? When I crank the engine with my multimeter set to Hz I don't get any reading off the TBI pin on the ECM, that is, until the engine is running (with the help of starting fluid) I tested the TBI with a test plug as well with the same results. I didn't get any light on the test plug until I got the engine to crank with the starting fluid.

I read that the ICM goes bad due to heat stress and since the previous owner said it over heated I figured this would be a good place to start. It was a fairly easy fix but it didn't solve any of my issues.

I also read that with the key on the SES light should come on. It doesn't. And when you crank the engine the engine (or maybe just on key on) the tach should read 300. Either way it doesn't.

When the car runs, sometimes it will throw codes but as soon as I turn off the engine the codes clear and the SES light doesn't come on with key on so I can't read the codes that were there. I tried to short the A/B on the ALDL anyhow and it doesn't work. I unplugged the battery for a while to reset the ECM, even though for a few days there was no battery installed while I got a new one. So resetting the ECM didn't help anything but I figured that while I was doing other things it couldn't hurt to do it one more time.

I think it's worth mentioning that the temp gauge sensor was shorted when I got the car. Could that have damaged the ECM? Could there be a bigger issue in the car that is frying the ECM's if this has already been swapped at least once?

I just read that having a dry battery connected for long periods could kill the ECM? The car was parked for 2 years with the same battery installed when I bought it.

I've been really really avoiding accepting that it might be the ECM because although they aren't terribly expensive they aren't terribly cheap and I have to justify the cost to my financial adviser ; ) And if it isn't the problem and I buy an ECM then I'm in the dog house.

I guess this post can just be a running post until I get permissions from the admin to make a new topic. I pulled the ECM this morning because I was 99% sure I was looking at a bad unit. Sure enough I've got what looks like a blown capacitor - labled C2. I was hoping to find a blown varistor(?) as I read it's an easy fix.

Does anyone happen to have info on this capacitor? The Ogre linked to an awesome site from his page that went into a lot of technical detail about the ECM but didn't give any capacitor values. If possible I'd like to try to swap in a good capacitor and see if that helps, if not, then I'll break down and get a new ECM.

Do you think it's even worth the effort of finding the value of C2 and soldering a new one in place (really not that much work) or would getting a new ECM be the best course of action? I'm still concerned that I'll plug the new ECM in and end up burning it up too.

Okay, I'm still not able to post, but I went to one of the 2 parts stores in town and they had 2 ECM's to choose from:

Remanufactured Cardone #77-6156 pre-programmed with a 1 year warranty

New Blue Streak #ECC6165 (OEM #1226165) pre-programmed with a 1 year warranty

Both are going to run me about $90 after taxes, but my question is, why is the remanufactured one the same price as the other? Is one better than the other?

Thank you for reading,

Javalin
IP: Logged
PFF
System Bot
phonedawgz
Member
Posts: 17011
From: Green Bay, WI USA
Registered: Dec 2009


Feedback score:    (23)
Leave feedback





Total ratings: 290
Rate this member

Report this Post07-14-2014 11:31 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Before replacing your ECM first check to see if you have power to the ECM. Most likely that is your problem.

http://cliff.hostkansas.com...ctrical-Diagrams.pdf

Check pins 10 and 15 WHITE to make sure you have +12v.

Key on check pin 16 for +12.

If you are interested I can send you an 84 used ECM for 45.80 shipped USPS Prioritty mail. email or paypal me at gofast@reddevilriver.com if you are interested. If you get it to me before 3P Central I will get it in today's outgoing mail.

[This message has been edited by phonedawgz (edited 07-14-2014).]

IP: Logged
Javalin
Junior Member
Posts: 2
From: Mojave Desert, California
Registered: Jul 2014


Feedback score: N/A
Leave feedback

Rate this member

Report this Post07-14-2014 04:41 PM Click Here to See the Profile for JavalinSend a Private Message to JavalinEdit/Delete MessageReply w/QuoteDirect Link to This Post
Pm sent.

When I get home I can see if that ecm is getting power but the c2 capacitor is definitely blown.
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock