Need help with wiring diagnostics (agent86...)

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Aug 19, 2008 | 12:57 AM

cwyates4

Thread Starter

Melting Slicks

Joined: Jan 2008

Posts: 2,065

Likes: 1

From: Jasper Texas

Need help with wiring diagnostics (agent86...)

I need an fsm!

Anyways, I'm really begining to question my ecm. heres why...

-It keeps storing code 24, the wheels haven't moved in a while!

For the last few months, it'll pop up about once a week randomly; doesn't light the cel, speedo is working fine...somethings fishy. theres more...

-I can't get my aldl to talk to my laptop. I can see everything except aldl data, and I have everything needed to do it correctly. still more...

-The car is running pig rich. I've found some problems and fixed them, hasn't changed a thing. Only way I can get the car to not run so rich is bring the tps down to a crazy low number, like .44v, and its still rich!

----

All these things can point to the ecm (a NAPA reman unit that has some years on it, probably 10 years old).

Anything in the fsm that tells a way to check voltage to determine a faulty ecm? Maybe if I just checked a bunch of sensors that should have 12v coming in, I'd see numbers all over the place...just don't know which wires to check without the fsm.

Thanks guys!

Aug 19, 2008 | 02:57 AM

86PACER

Le Mans Master

Joined: Jan 2003

Posts: 5,858

Likes: 7

From: Santa Maria CA

Here are Agent's scannings I found on Vader's site.

http://members.shaw.ca/corvette86/

Aug 19, 2008 | 06:31 AM

rons85

Burning Brakes

Joined: Apr 2004

Posts: 762

Likes: 2

From: Huntington ma

Still can't get TunerPro to see the ALDL data, huh? Try WinALDL - it's less "fussy" abuout the cable and connection. You'll have to run through the COM port choices to find where the data is coming thru at, and tell it the speed is 4K - that works with the '85 ECM, even tho it really is just a 160 baud modem..

I do think I have discovered the issue with the newer TunerPro - on my particular laptop the serial data is coming in on COM 5. That's where both WinALDL and TunerPro v4.13 see it. TunerPro V4.14, however, doesn't "see" the cable at com 5, it "sees" it on com 3. No Data there, tho. If I ignore the "cable not found" error and set it for com 5 anyhow, the data does come up - it works.

The other option would be to forget about all of this computer software based stuff and plug in a dedicated Scan tool. No questions about That working right - either it will see the ALDL data or the ECM/ALDL/Wiring is bad somewhere...

I forget (and the Book isn't here at work..) - what is a code 24?

Aug 19, 2008 | 08:23 AM

mk842766

Pro

Joined: Aug 2000

Posts: 666

Likes: 0

From: Richmond TX

Quote:

Originally Posted by cwyates4

I need an fsm!

Anyways, I'm really begining to question my ecm. heres why...

-It keeps storing code 24, the wheels haven't moved in a while!

If changing the TPS causes the fueling to change, then it's not your ECM. If the ECM was bad, then changing a sensor would not change how the car ran. I've had the same problems as you with the ALDL data stream on my 85, and the only way I was able to fix it was to re-wire the ALDL.....that 25 year old wiring was just crap. I've ended up replacing an awful lot of my wiring, and if I had to do it again, I'd get a new wiring harness, instead of replacing it piece-meal. BTW, code 24 is your VSS, and it will set that code, if you have the car running, but it is not moving. Once certain conditions are met, and the car is not at a speed set in the chip, the code will set. I found that with the 85 6870 ecm and chip, it set more often than the 7165 ecm and ARAP chip....so if you are still running the 6870 ecm, that may be your code 24 problem. I think you've still got some problems with your engine, and if I was guessing, it's a vacuum leak. Check close...

Cheers,
Michael

Aug 19, 2008 | 08:27 AM

rodj

Le Mans Master

Joined: Aug 2000

Posts: 8,838

Likes: 31

From: Australia

Quote:

Originally Posted by rons85

the serial data is coming in on COM 5. That's where both WinALDL and TunerPro v4.13 see it. TunerPro V4.14, however, doesn't "see" the cable at com 5, it "sees" it on com 3.
what is a code 24?

TunerPro doesn't "see" a Coms port; you have to go into Preferences and nominate the port so it is the same as what your laptop is using.
Com 3 is just what it comes set to ; each laptop could be different depending apon equipment installed.
Mine is Com 2 on the serial and Com 5 if I use the USB cable.

Code 24 is VSS; open or no activity

Aug 19, 2008 | 09:19 AM

AGENT 86

Team Owner

Joined: Jan 2003

Posts: 20,324

Likes: 250

From: Summerland B.C. Canada

My ECM info is for a 165 ECM. Maybe this info will help.
http://chevythunder.com/fuel%20injec...ecm%20#1226870)
No one in your area that can lend you an 85 ECM.