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2000 STS with electrical problems?


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ok so i just bought this cadillac and i already love it even though it has a ton of problems. to start off, the dash says check engine, check air bag, check coolant level, and service the A/C system. the check engine light is throwing codes: P1032, P0741, P0174, P0155, P0030, P1031. also the gas gauge doesnt work, the majority of the time it stays at completely full no matter what. The coolant seems to be going fast, but my oil isnt milky. the running temperature of the engine is usually exactly half way. for the electrical problems: sometimes the speakers sound blown but they arent, passenger power mirror doesnt move, entire drivers seat doesnt work (doesnt move and no heated seat but the seatbelt indicator works) the steering wheel adjustment does not work, when i press the unlock button on drivers door, only the drivers door will unlock and lock. only drivers window goes up and down. the lights on the buttons on the other doors are not lit up. all fuses seem to be fine. exhaust tip is wet and when i touched the inside with my finger my finger was all black. apparently it would burn through oil pretty quick, previous owner rarely got oil changes. my horn works and steering wheel controls work. defrosters work. i noticed that the heat has virtually no air flow, its as if i had it on the lowest setting when i have it on the highest. I think all these problems are linked to one thing but i do not know what it is, please help. i want to restore this cadillac, not sell it to a junk yard.

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Wow, where to start.

First off welcome to caddyinfo forum.

I would pull all of the codes from all of the computers. there are several. I am willing to bet you have door module codes, RIM(rear integration module) codes, may even have a datalink problem between computers. The codes you pull will explain more.

Pull up the back seat, I believe there is a fuse box there and the battery is under the seat also.

As for the fuel gauge Run a bottle of chevron techron in the next fillup. Should help.

The disappearing coolant would have me worried, you dont see and visible leaks? common leak points are radiator tanks, heatercore, reservoir, and radiator cap. Try replacing the surge cap and see if it helps.

I would pull all of the codes, then unhook the battery, leave it unhooked for about a minute and see what issues come back. Can make a world of difference. Then pull new codes.

Best of luck to you. Hope this helps without going too crazy

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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thanks haha, and yeah where to start is right. ill try the fuel system cleaner, and i cleared to codes before i checked them again. am i looking for all "current" codes? im use to working on cars but i have no idea where to begin with the electrical, im assuming its the modules but idk which ones and with the price of cadillac parts i cant afford to replace parts that are still good

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The modules don't give trouble unless you do something like hook jumpers up backwards or put a fast charger on the battery while it's connected, or use a continuity tester or the wrong meter on the wiring harness on a static-sensitive terminal. Changing a module because of a code, AKA shooting the messenger, won't fix the car. The OBD system on any car sold in the USA since 1991 makes hundreds of checks on the car's functioning every second. Emissions laws require that certain tests be performed and that the MIL ("check engine soon" light) be turned on if any of those fail, but these are among those that affect the DFI or transmission and the manufacturers would want the MIL turned on anyway. Every time any warning light turns on, it's because some OBD test failed, so a check of OBD codes will tell why the light was turned on. This is an enormous troubleshooting help, and makes online help like we do here on Caddyinfo effective.

P0030 Heated Oxygen Sensor (H02S) Heater Control Circuit Bank 1 Sensor 1
P0155 Heated Oxygen Sensor (HO2S) Heater Performance Bank 2 Sensor 1
P1031 Heated Oxygen Sensor (HO2S) Heater Current Monitor Control Circuit Banks 1 and 2 Sensor 1
P1032 Heated Oxygen Sensor (HO2S) Heater Warm Up Control Circuit Banks 1 and 2 Sensor 1

P0741 TCC System Stuck Off
P0174 Fuel Trim System Lean Bank 2

The first thing I would do is to check the 10 Amp OXY SEN fuse in the under-hood fuse block. Although all your reported codes are for Sensor 1 and there are no codes on Sensor 2, sometimes the PCM won't throw a code for conditions like Sensor 2 failed but there is already a code for Sensor 1. If the fuse is good and, with the key on and a cold engine not running, the oxygen sensors aren't warm to the touch after five or ten minutes, you might check and see if they have battery voltage on the PNK or DK GRN wire and ground on the BRN, BLK, or BLK/WHT wire. Any oxygen sensor that has battery voltage to it and ground on the ground terminal and doesn't get warm is bad and should be replaced. Use the AC/Delco oxygen sensors for long life.

The P0741 means that the TCC isn't engaging on the transmission. This can mean that a shift solenoid isn't connected or has broken or is sticking, but usually throws another code, which I don't see here. A bad TCC can be ignored unless you are going to tow or drive in the mountains or some such, so look at it last.

The P0174 without an accompanying P0171 usually means an air leak in the intake manifold, although I would check the PCV hose and valve, and make sure that the dipstick is seated and the oil filler cap is tight before I looked at anything more difficult.

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-- 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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the codes i am getting in order are:

DDM U1161 CURRENT - loss of pass. door module

DDM U1162 CURRENT - loss of rear driver door module

DDM U1163 CURRENT - loss of rear pass. door module

DIM B1321 CURRENT - driver door ajar circuit short to battery

NO MSM DATA

PCM P0030 CURRENT - HO2S heater control circuit bank 1 sensor 1

PCM P0155 CURRENT - HO2S heater performance bank 2 sensor 1

PCM P0174 CURRENT - Fuel trim system lean bank 2

PCM P0741 CURRENT - Torque Converter clutch circuit performance or stuck off

SDM B0051 CURRENT - Deployment commanded

SDM B0058 CURRENT - right front/passenger pretensioner deployment loop open

SDM B0065 CURRENT - left front/driver pretensioner deployment loop open

SDM B0077 CURRENT - left front/driver frontal deployment loop open

SDM B0078 CURRENT - passenger side impact sensor (SIS) malfunction

SDM B1000 CURRENT - ECU malfunction

NO TTM DATA

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wow. thats alot of codes. I would disconnect the battery and recheck them again. The door ajar shorted to battery is an interesting one because they are supposed to be negative. I am curious if someone has installed a remote car starter and something is messed up. Do you know if it has a remote start? or aftermarket stereo.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Here's what I have for your CURRENT codes. Note a big difference for the B1321, which I verified with the 2002 FSM.

U1161 Loss of PASS Door Module SBI
U1162 Loss of Rear Driver Door Module SBI
U1163 Loss of Rear PASS Door Module SBI
B1321 A/C Low Side Temperature Sensor Fault

There are other network codes. The NO MSM DATA message means that the memory seat module doesn't respond to network signals. Since it's operated from the network, it's dead unless it can talk to the network. All of the Unnnn codes are network codes, and all three of yours are CURRENT and related to all of the doors but the driver's door. The acronym SBI is serial bus interface, which is the network signal line.

The B1321 set from the DIM is the A/C temperature sensor warning. You should get the message "SERVICE A/C SYSTEM." This sensor is on the A/C compressor hose on the low side, which is the hose going back toward the firewall. The high side hose goes to the condenser which is in front of the radiator. Make sure that the connector to it is clean and tight. If you have a DVM that is safe for static-sensitive circuits, you can use it to check the voltage on the GRY wire on the sensor. The code is set whenever that voltage is below 0.1 Volt or higher than 4.9 Volts. With the sensor unplugged and the engine off but the key on, the PCM should supply 5 Volts to the GRY wire. They didn't give a resistance to check for the sensor because that number varies a lot with temperature, but it should not be an open circuit (over 1 MegOhm) and both sensor terminals should show no connection (open ciruit) to ground with the wiring harness disconnected.

I closed the FSM before I checked, but I believe that the network line is nearly always the PPL wire. Check the wires to the doors, particularly at the points where the wiring goes through the hinges.

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-- 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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The MSM operates the power seats. The switches for the power seats all go to the MSM. Voltage for all the power seat switches goes through the 10 Amp MEM T&T fuse in the rear fuse block. The power seats themselves get power through a 30 Amp circuit breaker in the same fuse block; circuit breakers self-reset and rarely go bad. If everything is dead, I would check the fuse. If it is good, look for connectors to the MSM, which is under the driver's seat.

While you are looking at fuses in the rear fuse block, check the 10 Amp PASS MDL switch; it powers the front passenger door module (FPDM) and may be the cause of the U1161. Also, there is a 10 Amp fuse labeled RRDR MDL that powers both left and right rear door modules and may be the problem causing your U1162 and U1163.

There are a bunch of air bag codes, the SDM codes, that need to be looked at too. The B0051 indicates that the car has been in an accident of sufficient severity to deploy the air bags. You can ask a dealer about this and he can use the VIN to check and see if this is the case, or if this is a false code. The other SDM codes may indicate that air bags deployed but were not replaced.

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-- 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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I checked connections by doors and they all checked out fine. On my way to work everything was acting up like my radio kept turning off and my door would only work sometimes when the accessory was on, I pulled the panels off and found 2 loose grounds, tightened them and disconnected the battery and reconnected it after five minutes and I had the same problem, disconnected the battery again for like 15 while I put the panels back on, reconnected battery and the issue was fixed. I will check the one fuse after work. Everytime I take off the coolant cap there is no pressure? Even when the engine is hot? Isn't there suppose to be pressure? Also my abs and traction control lights when on at the same time? But when I first start my car I have like a minute before traction control comes on after I reset codes, traction control works when the light isn't on. It's like it got disconnected or something, all wires under the drivers seat are connected.

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The car has been in numerous minor accidents, I don't think they were sever enough to deploy the air bags. I appreciate your help guys, I have no idea where the modules are located, if anyone has any wiring diagrams that might help me pinpoint disconnected wires or faulty modules. Also, the passenger power seat works fine, along with the heated seat. But all doors except drivers door are dead, except when I open the drivers door, the light on the passenger door comes on as it should.

Edited by gabrielslezak
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The MSM is a box under the driver's seat. Look for a box with a big connector to the wiring harness.

If a couple of grounds were bad, I would not trust any ground. Or any power lead, or any fuse. We'll keep that in mind from here on.

You need your own FSM for this car because it has a lot of little things. People here have to find your page, scan it in, save the photo on their HD, upload it on Photobucket or other service, and then post that photo here every time you need a schematic or page. I suggest eBay for price and availability.

I just looked at my SI DVD for the 2002 Seville (the closest to your car that I have on hand) and find that there are 19 figures that show wiring ground schematics. There are 24 power, ignition switch, and fuse diagrams. There are links on these diagrams to drawings that show locations. This is a DVD, but similar information is in the paper manuals. If you are serious about restoring this car yourself and don't want to spend a lot of money doing it, you will NEED the factory shop manuals. There is absolutely no substitute.

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-- 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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Found an FSM for $25 on ebay. Thanks for the advice. i also get an odd burning smell from the engine. i think it might be oil. my sts had a motor swap from a dts, but i believe they are the same engines. is the dts known for blowing head gaskets also? i got that relay and i am about to put it in, i will keep you posted.

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Which model DTS did you get the engine from?

Head gasket failures are rare, high-mileage events, particularly if you keep the coolant changed regularly. The first symptom is increasing coolant loss over a few months, with no leaks being found.

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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so i replaced the relay, the circuit breaker, and some of the fuses even though they were still good. took off drivers seat cushion and looked at the msm and it looked fine on the inside, nothing looked out of place, i reconnected all the wires and still nothing. no power seat controls and steering wheel still doesnt move. seat warmer stil doesnt work. could the rear door modules and the passenger door modules be linked to the drivers seat in any way? i know its getting power cause i tested it with a volt meter. my passenger mirror does not move but my drivers mirror does. so it must have something to do with where the mirror goes to also. but the foot lights on the door work, so are they not connected to the passenger door module? its odd that thats the only thing that works, when every i open any door other than the drivers door, the interior lights do not come on. the car doesnt know the door is open.

Edited by gabrielslezak
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We'll just go with 2000 STS in our manuals and such for your car because the replacement engine is obviously compatible, and the problems don't seem to be caused by incompatibility.

You should know that there are two flavors of Northstars, VIN "Y" or RPO LD8 which is 270 or 275 hp, and VIN "9" or RPO L37 which is 295-320 hp. The STS (and any other Cadillac with a "T" as the middle letter in its model name) will have a VIN "9" engine. The only difference in the 1993-1999 was the intake cam; int the 2000 up engines both cams are different.

It would be hard to tell the difference once the car is together and running, so I wouldn't concern yourself. There may be a VIN derivative on the engine somewhere if you want to check.

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-- 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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idk what model dts, all i know is its from a dts, thats the way i got it and it says dts in the mechanics paint with the miles that was on it before it was swapped

So, it's from a DTS, so it's a VIN "9" engine, which is the right one for your car, an STS.

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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If you are talking about changing the MSM, it's mounted to the floor, not the seat. I would imagine that the problems with it are a fuse, a connector or a ground, not the module.

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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What current codes do you have? I remember that an orange wire would break in the pass thru grommet from body to door and would kill that door and others because the circuit ran in series and like a xmas tree bulb if a wire broke in a door it took them all out.

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i havent noticed any broken wires. my msm is under my seat like the one guy mentioned, there isnt a module mounted to my floor. the codes i am getting in order are:

DDM U1161 CURRENT - loss of pass. door module

DDM U1162 CURRENT - loss of rear driver door module

DDM U1163 CURRENT - loss of rear pass. door module

DIM B1321 CURRENT - driver door ajar circuit short to battery

NO MSM DATA

PCM P0030 CURRENT - HO2S heater control circuit bank 1 sensor 1

PCM P0155 CURRENT - HO2S heater performance bank 2 sensor 1

PCM P0174 CURRENT - Fuel trim system lean bank 2

PCM P0741 CURRENT - Torque Converter clutch circuit performance or stuck off

SDM B0051 CURRENT - Deployment commanded

SDM B0058 CURRENT - right front/passenger pretensioner deployment loop open

SDM B0065 CURRENT - left front/driver pretensioner deployment loop open

SDM B0077 CURRENT - left front/driver frontal deployment loop open

SDM B0078 CURRENT - passenger side impact sensor (SIS) malfunction

SDM B1000 CURRENT - ECU malfunction

NO TTM DATA

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Since you don't believe that the air bags were ever deployed and we have an SDM B1000, perhaps it's time to reset all the modules. You can check with either a CarFAX or from a GM dealer whether your car's VIN has ever been in an accident where the air bags deployed.

Disconnect the negative terminal of your battery, then disconnect the positive terminal of the battery. Leave them disconnected for several minutes. Then reconnect the positive terminal, then, last, the negative terminal. Drive the car, then check the codes again before turning off the key.

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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