Author Topic: 1981 Eldorado 368 8-6-4 code 18  (Read 764 times)

Offline Tonyv_73

  • Posts: 66
  • Name: Anthony Vanacore
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #20 on: February 04, 2018, 12:08:48 AM »
Okay so just to clear up my issue, my car runs pretty much perfect, I drive it with the 8-6-4 plugged in, almost every time I drive the car my check engine light will go on and code “18” will show up in the computer. I reset it and sometimes it will go away and sometimes the code will come back. What should I look at in reguards to the engine? I had a tune up done on the car which included cap, rotor, plugs, wires, etc.  I should also note the only other issue with the car is when I get gas the gas spits back up the neck. I assumed that the sending unit will most likely need to be replaced because the tank is not getting ventilated.  I am only mentioning this in case it has some connection to the code 18 issue.  Also I have not changed the injectors so if that helps let me know.
1973 cadillac eldorado convertible
1963 cadillac deville convertible
1966 cadillac Calais sedan
1970 buick wildcat

Offline smokuspollutus

  • Posts: 106
  • Name: A. Molinaro
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #21 on: February 04, 2018, 08:23:51 AM »
Tony, as was mentioned this code has nothing to do with mechanical parts, so I would disregard the tune up as a possible cause. When you turn the key all the way forward to crank the engine, a reference signal goes to the ECM. Unlike a lot of the wiring going to it, GM thoughtfully included a fuse on this circuit. Check if you have 12 volts to this circuit while cranking, then check the fuse. My bet is they will both check out ok, and the problem lies in a bad connection on the ECM. Clean up the contacts and re-seat the it.
1984 Eldorado Biarritz Coupe

Offline Dave Shepherd

  • Posts: 1977
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #22 on: February 04, 2018, 08:42:07 AM »
Interesting about the stalling issue, at that time when I worked for Cadillac in NYC, we had multiple complaints about stalling, very hard to reproduce, but one common cause was the baffle in the gas tank that the pick up sat in broke loose and  would block the fuel flow under certain conditions.

Offline jsanford

  • Posts: 53
    • CLC Member
      CLC Member #28692
  • Name: Jeremy Sanford
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #23 on: February 04, 2018, 10:03:59 AM »
Tony,

Amazing how any time someone has any sort of trouble with a L62 equipped car the comments instantly go to what a disaster the engine was  ::)

I have attached the trouble tree from the SM so you can give it to your mechanic. Good luck getting it sorted out.

Jeremy
Jeremy
Sacramento, CA
1981 Eldorado
2016 ELR

Online Eric DeVirgilis CLC# 8621

  • Posts: 4121
    • CLC Member
      CLC Member #8621
  • Name: Eric DeVirgilis
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #24 on: February 04, 2018, 11:16:22 AM »
https://www.leagle.com/decision/198350593nj412184

http://caselaw.findlaw.com/ca-court-of-appeal/1770877.html

https://www.newspapers.com/newspage/6380730/

Thanks for the detective work. (I only said I have no recollection; not that it did not happen.)

If any car deserved having a lawsuit being filed over, it should've been the HT4100.  :o

Amazing how any time someone has any sort of trouble with a L62 equipped car the comments instantly go to what a disaster the engine was  ::)

Indeed. 
A Cadillac Motorcar is a Possession for Which There is no Acceptable Substitute

Offline TJ Hopland

  • Posts: 6941
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #25 on: February 04, 2018, 11:22:33 AM »
Since there is a fuse in that circuit I would check that close.  Recently on a much newer vehicle with that style fuses I had intermittent issues that turned out to be what looked like tarnish on the fuse blades itself.   I say tarnish because it didn't clean off with a wire brush like normal corrosion.  Slapped in a new fuse and all was well.  The socket looked fine. 

Its interesting that they put that fuse where they did.   I wonder if that is maybe to protect the wire when it comes inside the car vs under the hood?   There isn't likely much of a load so it won't take much of a bad connection to screw it up.

Where is that '56 way' physically located?     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Tonyv_73

  • Posts: 66
  • Name: Anthony Vanacore
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #26 on: February 10, 2018, 11:32:23 AM »
Just drove my car to get lunch, when I finished and started my car I was idle for about 10 minutes and I got a bunch of codes

19
23
24
25
32
44
45

I looked them up and they’re all pretty much from a short, anyone have any suggestions as to where this short could be?
1973 cadillac eldorado convertible
1963 cadillac deville convertible
1966 cadillac Calais sedan
1970 buick wildcat

Offline TJ Hopland

  • Posts: 6941
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #27 on: February 10, 2018, 12:35:15 PM »
Its really unlikely to have that many codes that are not related so you have to find out how they are related.  Start by finding what all those codes / sensors have in common.    Do they all have a common ground point perhaps?   All run into the same loom?   Same bulkhead connector?   Same connector at the ECU?   

I have not looked at them for a while but I remember the electrical parts of the service manuals in that era were pretty well written since at the time no one was used to dealing with the computer stuff.   They gave a very specific sequence to trouble shoot which if that doesn't solve the issue on its own would give you indications how the things relate to each other.   For instance the first like of say code 99 would be to make sure you don't have a code 77, if you have a 77 fix that first.  That would tell you that what ever sensor or module 99 is likely depends on 77 working correctly. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Glen

  • Posts: 2296
    • CLC Member
      CLC Member #727
  • Name: Glen Houlton
Re: 1981 Eldorado 368 8-6-4 code 18
« Reply #28 on: February 11, 2018, 01:24:33 AM »
After troubleshooting multiple codes on the “02 Buick antilock brake system, I removed all the grounds, cleaned and replaced them.  No more trouble codes.   Maybe you could try that. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

 

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