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Electric problem with my Cadillac Seville 1991


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Hi

I have a serious electric problem with my Cadillac Seville 1991.

Dash light, headlight, flickering, when engine off, sometimes even radio turns on.

What can be the problem and how to fix it?

When ignition on or engine running I don't have any problem.

When engine off and trunk open, no problem. Could this point in a direction to a bad relay somewhere?

Codes that I got E052 History and B552, No SIR codes but I think they are related to that I have to switch off battery when leaving the car.

My local repair shop have replaced ignition switch (steering column), but still problem.

I have checked for bad grounds (G103 –starter motor, G400 Trunk) but so far this hasn’t helped

Where to start/continue searching?

My local repair shop has no idée when it comes to electrical problems and refuses to work/help with my car anymore…..

Swedish member in trouble

Help needed

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I would check all grounds and power connections, it sounds like you are getting an intemittant connection

I would also pull all breakers and fuses and check for corrosion and check them for continuity

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

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Yep,

This is one of those issues where you need two people.

One watches the dash & listens to the radio while the other (with a keen eye) moves around wires, and wiggles connectors under the hood, dash & car. as BBF said, look for corrosion, greese, splits & dirt/oil where it shouldn't be. removing a fuse at a time should help track down the circuit that's feeding the juice to the mystery.

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Yep,

This is one of those issues where you need two people.

One watches the dash & listens to the radio while the other (with a keen eye) moves around wires, and wiggles connectors under the hood, dash & car. as BBF said, look for corrosion, greese, splits & dirt/oil where it shouldn't be. removing a fuse at a time should help track down the circuit that's feeding the juice to the mystery.

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We have started to check as suggested but so far no findings which can explain the problem.

But what we have seen is

- In each rear lights (bulb) there are two emitters and (running lights and brake) and for a short while all 4 running lights where on except for one where the brake was on. Then we removed the bulb and put the bulb back again and the correct emitter was on, running lights. Can’t explain why(?!)

- The problems come and go when engine and ignition off and key removed from switch.

- When it seems to be OK then ,and then when I open the driver door, the problem will sometimes come again.

- If I open trunk the flickers always stop and everything is OK.

- If I start engine the flickers always stop and everything is OK.

//Conny

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We have started to check as suggested but so far no findings which can explain the problem.

But what we have seen is

- In each rear lights (bulb) there are two emitters and (running lights and brake) and for a short while all 4 running lights where on except for one where the brake was on. Then we removed the bulb and put the bulb back again and the correct emitter was on, running lights. Can’t explain why(?!)

----------------------------------------------------------

Hi Conny,

I would first make sure the ground connection at that particular tail light is clean and tight.

If a ground is bad then the electricity ends up going through the other filament.

Your whole problem sounds weird for the self activating issue.

My 91 STS had a strange problem of very rough running for the first 10 minutes each morning.

Even the dealer gave up and didn't charge me anything, and that was after also replacing the computer.

I finally did a good diagnostic and found that the ground to the block wasn't working even though it was clean and tight.

Most of the grounds (circuit returns) up front go to the fender side behind the battery. (Black wires on screws to the body.)

The others I haven't studied yet and are probably in the trunk.

Good luck,

Bob B

- The problems come and go when engine and ignition off and key removed from switch.

- When it seems to be OK then ,and then when I open the driver door, the problem will sometimes come again.

- If I open trunk the flickers always stop and everything is OK.

- If I start engine the flickers always stop and everything is OK.

//Conny

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  • 2 weeks later...

After a short vacation to add strength to continue to search for the electric problem my investigation continues.

- No trailer connection

- All fuses checked and OK

- Harness to rear lights disconnected put still problem

-

Tomorrow is another day to find the problem without a real idea how to work in a structured way :blink: , I will start with

- Removing fuses, one by one to see what happens

- Pull all breakers, where to start?

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For a good time, remove the battery and recondition the battery cable terminals. While the battery is out, take it to an appropriate shop and have it tested.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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All fuses checked

Relays checked

Problem seems to be related to BCM (Body Control Module), next step will be to replace BCM to “new” one. Old BCM sends strange +current to accessory relays, not constant.

Trying to find tool to remove Prom from old BCM

Anything that I have to have in mind when replacing a BCM?

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I've never heard of a BCM going out, short of someone hooking up jumper cables backward or some such.

FWIW, the BCM doesn't send power to relays, but grounds one terminal of a coil through an IGFET. Relay power is through a fuse.

If you haven't read the OBD codes yet, you are missing out on all the car can tell you about the problem(s).

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Correct Jim, BCM was not the solution.

- Battery removed and we have recondition the battery cable terminals

- Some new cabels where possible to change

- OBD codes checked, got B420 no other codes

- Ground behind battery (G100,G105) close to starter (G103), Rear of trunk (G400) cleaned

- All relays and fuses on interior Relay center checked and OK

Central power supply (CPS)how to check if BCM will be corrected feeded

Or what to do......::?

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The B420 seems to be a network error, probably in sending memory set settings when you used fob no. 1. Are you reading the codes from the dashboard or are you using a code reader?

I don't have a factory shop manual on an OBD I car so I don't know anything about the Central Power Supply. But, the BCM has its own voltage checks and will throw a code if its battery voltage is low or high. There is something called the CPS in OBD II codes that appear to have something to do with child seat detection for the air bag system.

One simple DIY way to find out if a fault has been corrected is to make sure that any remaining codes are HISTORY and not CURRENT, then reset the codes and see if they come back.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Great, that means you're getting them all. Hand-held code readers under $150 just give you the Pnnn or Ennn codes that relate to emissions. The bad news is that the two codes that you do have only tell us that the battery voltage is intermittent. When the battery voltage drops too low all the codes are reset except the E052 and B552. That seems to be telling us that the flickering you are seeing when the engine isn't running is in the battery cables or one of the Maxifuses, not in the wiring or relays.

The main mystery to me is why you don't see flickering when the trunk is open.

P052 (E052) PCM Memory Reset

B552 BCM Memory Reset Indicator

B420 BCM Output Driver 1 Failure

If the battery voltage is stuttering, as the E052 and B552 seem to tell us, things like the B420 (or just about anything else) as well as the erratic behavior of the BCM are the result. So, for now, let's look at making sure that the battery voltage is steady and OK.

There are three battery cables running from the positive terminal of my battery (1997 model year). One goes to the alternator charging terminal, one goes to the starter relay, and one goes to the Maxifuse block and powers the car. The fact that your car starts without problems and is OK when the engine is running tells us that the positive terminal is OK, and that it is connecting to the battery. The alternator is picking up the slack when the battery voltage drops off.

This leaves the battery ground cable as the most serious possibility, with another being the engine ground strap. A third possibility is a short in the wiring harness that is affected when the trunk lid is down. This points to checking both ends of the battery ground cable, and finding the engine ground strap and checking it and its connection at both ends. If they are OK, pull the trunk liner out and see if the trunk lid hinges are touching any wires when the trunk lid closes.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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