themkanes Posted November 7, 2008 Report Share Posted November 7, 2008 96 Deville with 92000. I just first wanted to say thanks for all the valuable knowledge gained on this site since I joined last year. All your expertise was helpful many times over. I've been able to troubleshoot most of the problems I've had with my Caddy from this site. All except for this one...... I've been having an intermittant electrical problem which causes the IPC not to light up. this could occur when 1st starting it or going down the road and the IPC flashes on and off. When the IPC does not light up and the car is started it will start for a few seconds and then stall. I've determined that this is the anti theft feature shutting down the fuel delivery. When this occurrs it throws a 1604 loss of IPC serial data code but I am unable to determine the root cause of the problem. It would seem to me to be a faulty connection or ground. What seemed to help would be to clean the battery terminals, this seemed to correct the problem in the past, however, I again started having this problem yesterday and cleaned the terminals and it worked great yesterday, however this morning same thing, no IPC lights, starts for a few seconds then shuts off, throws code 1604. What I'm thinking is possibly a bad negative battery cable ground, because when manipulating the connections, it seems to correct the problem. However, there is no "instant manipulation" that works, what I mean by that, is I can't tighten a cable and see immediate results, however, if I tighten a cable, walk around to look at the dash it can be out but when walking back to the battery, it will suddenly come back on. When driving the car and IPC goes out and I shut off the car it will do the same start and shut off routine IF i remove the key from the ignition. If I leave the key in the ignition and shut the car off with the IPC out I can restart the car and it will continue to run whether or not the IPC is illuminated or not. So, after many hours spent researching this subj, I submit to you my 1st post. Thanks for any help you can provide as to where to begin and what areas or grounds or conections I should be checking. Thanks Again. Link to comment Share on other sites More sharing options...
themkanes Posted November 16, 2008 Author Report Share Posted November 16, 2008 Well, the woes continue. Now today the IPC won't light up at all and of course it starts for a moment and then shuts off. I'm assuming it's still due to P1604. Loss of IPC serial data. Before it was an intermittant issue, now a full time issue. It is not a battery/terminal related issue. Any thougts on trouble shooting the loss of serial data to the IPC. Any help or a push in the right direction would be greatly appreciated! Link to comment Share on other sites More sharing options...
BodybyFisher Posted November 17, 2008 Report Share Posted November 17, 2008 Well, the woes continue. Now today the IPC won't light up at all and of course it starts for a moment and then shuts off. I'm assuming it's still due to P1604. Loss of IPC serial data. Before it was an intermittant issue, now a full time issue. It is not a battery/terminal related issue. Any thougts on trouble shooting the loss of serial data to the IPC. Any help or a push in the right direction would be greatly appreciated! I would try resetting all plugs at the IPC first Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
themkanes Posted November 19, 2008 Author Report Share Posted November 19, 2008 After many many hours checking and diagnosing this issue I seem to have found the answer. Simplest thing in the world. Minor corrosion on the fuse in the trunk, cleaned up the contacts and no further problems. Glad to finally have this one behind me, I've done so much research on Trouble Shooting Serial Data issues......oy...... that I'm finally glad this is behind me. Came upon this answer by reading another post on this site where somebody had an issue with another module, he came to answer by fixing a problem with his turn signal of all things. This made me think, when I have that issue with the IPC I also noticed that the steering wheel controls also did not work. Got the wiring diagram from Aldata, traced it down......and guess what. The IPC and the steering wheel controls get power from the same circuit but use different grounds, only one thing left it could be. Cleaned up the terminal, reinserted the fuse, not a glitch since. 2 days now without problems. I think I'll need to go a week before I'm really at ease but I think that's the problem. Moral of the story is don't overlook the simple things in your troubleshooting. I figure I've got about 15 hours time into this little problem. About 10 were dedicated to battery terminal, battery cable, battery ground related troubleshooting and replacement with no help. Finally glad to have gotten to the bottom of this issue. Thanks for a great site it has been a great help to me! Link to comment Share on other sites More sharing options...
lothos Posted November 19, 2008 Report Share Posted November 19, 2008 Thanks for posting the fix, I'm sure it will help out others in the future. WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn. Cheers! 5% discount code at RockAuto.com - click here for your discount! Link to comment Share on other sites More sharing options...
BodybyFisher Posted November 19, 2008 Report Share Posted November 19, 2008 Good for you, I think that is where we should start all electrical diagnosis, we have seen a lot of problems caused by corrosion. Glad you figured it out, thanks for reporting back your results Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
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