1999 Cadlillac Deville MIL back on

[Steve Ferraz]

A few weeks ago I mentioned that my Caddy's MIL light came on before I could do my emmissions test. I cleared the codes and later passed the test.

Now today the light came back on. Again I checked the codes on the dash and they came out all as history, but this time I wrote them all down. It came out to 10 codes (2 were the same) from "history", none current.

Here are the codes listed in the computers memory:

P0125

P1605

U1255*

U1152

B1148

B2470*

B2477*

U1301

U1255*

B2144

* these are old codes

I have a vague understanding of the first two but the rest?

Which ones would need immediate attention and which ones I don't need to worry much?

Thanks.

[barczy01]

B1148 is for passenger airbag system. B2144 Left Front Mirror Vertical Position Sensor Circuit Low. U codes are class 2 serial data. I would have the B1148 looked into might be a SDM under front passenger seat.

[Cadillac Jim]

P0125 Engine Coolant Temperature (ECT) Insufficient for Closed Loop Fuel Control
P1605 Loss of HVAC Serial Data
U1255* Class 2 Communication Malfunction (Serial Data Line Malfunction)
U1152 Loss Of ACM Serial Data Communication
B1148 Passenger Side Air Bag System Malfunction
B2470* Daytime Running Lamps Fault
B2477* Reverse Lamp Relay Shorted to Ground
U1301 Class 2 Short to Battery
B2144 Left Front Mirror Vertical Position Sensor Circuit Low

The module that throws the U1255 code will tell you which network line or module has the fault.

The P0125 will turn on the MIL. It probably means that the thermostat is stuck open or missing.

Like barczy01 says, look at the B1148. It's safety related.

[winterset]

Could be:

an age related corrosion problem under the fuse panel in the engine compartment

a bad battery connection between the 2 red cables at the post, or a bad ground

an aftermarket component that messed with the "purple data wire"

Check for green corrosion in as many places you can including under the fuse panels.

What it sounds like from the u1301 is that somewhere, the red+ is coming into contact with a purple wire.

Did you have work done recently? If so, start there, and look for damaged wires and connectors.

[rockfangd]

The ECT is your biggest problem causing the light.

Running in open loop is not a good thing.

If the coolant temp does not reach a certain temp by a certain time it will trip a code. 2 most common causes are missing or damaged thermostat, or faulty ECT sensor .(but I havve not run into one on a northstar yet).

Sometimes people have overheating issues and they jump to removing the thermostat, Not a good thing in todays vehicles.

How long have you had this Cadillac?

Running in open loop causes higher fuel consumption,

improper burn in exhaust,

egr issues,

etc...

Have you had any heat issues? What does your coolant temp show after about 10 minutes of run time?

I might add that you would likely not have been able to get it through emissions test without going into closed loop due to the monitors not all clearing without being in closed loop

[Steve Ferraz]

The ECT is your biggest problem causing the light.

Running in open loop is not a good thing.

If the coolant temp does not reach a certain temp by a certain time it will trip a code. 2 most common causes are missing or damaged thermostat, or faulty ECT sensor .(but I havve not run into one on a northstar yet).

Sometimes people have overheating issues and they jump to removing the thermostat, Not a good thing in todays vehicles.

How long have you had this Cadillac?

Running in open loop causes higher fuel consumption,

improper burn in exhaust,

egr issues,

etc...

Have you had any heat issues? What does your coolant temp show after about 10 minutes of run time?

I might add that you would likely not have been able to get it through emissions test without going into closed loop due to the monitors not all clearing without being in closed loop

I've had this Caddy for 2 years and this is the first time this code came up. (okay maybe second time, I didn't pay too closely a month ago on the codes because it was under "History")

I'm going to agree with you about the thermostat. Last month, after one bad snowfall, I got my car stuck in the driveway entrance and the thick snow was high enough to tough bottom of the engine. I kept rocking the car to get it moving and a few times revved the car quite high. Once I managed to move it, I noticed some drops of coolant on the snow. But the leak somehow stopped some time after refilling the reservoir. Found it weird. But looking back, I'm guessing while revving the engine the thermostat stayed open and released some of the coolant?

I haven't had any issues regarding heat and the car has not overheated. I cleared the codes three weeks ago and drove a bit before passing the emissions test.

As for coolant temp after 10min of run time, I'll let you know later today. What would be the normal temp?

[Steve Ferraz]

Could be:

an age related corrosion problem under the fuse panel in the engine compartment

a bad battery connection between the 2 red cables at the post, or a bad ground

an aftermarket component that messed with the "purple data wire"

Check for green corrosion in as many places you can including under the fuse panels.

What it sounds like from the u1301 is that somewhere, the red+ is coming into contact with a purple wire.

Did you have work done recently? If so, start there, and look for damaged wires and connectors.

Last time I had work done was last fall to replace a bearing in the front passenger wheel.

It has been about a year and a half since I had eletrical work done.

[winterset]

Ok. Easiest thing to do first is to disconnect the battery ground, then the red cable. The red is two cables. Separate them at the top, and clean them good. Then clean the battery terminals. Then connect the red, then connect the ground. The connections should be good and tight.

[rockfangd]

normal operating temp is between 190-205.

If you have a floor shift model with the guess the temp readout(lol) 12 oclock is good. Technically it runs just a hair over the line on the gauge..

[Steve Ferraz]

normal operating temp is between 190-205.

If you have a floor shift model with the guess the temp readout(lol) 12 oclock is good. Technically it runs just a hair over the line on the gauge..

At almost 10 min run time (roughly 8 minutes) the temp was around 179 - 183.

[Steve Ferraz]

Ok. Easiest thing to do first is to disconnect the battery ground, then the red cable. The red is two cables. Separate them at the top, and clean them good. Then clean the battery terminals. Then connect the red, then connect the ground. The connections should be good and tight.

What battery ground? I only know of the negative and positive battery cables.

[winterset]

Disconnect the negative first then the positive, clean both cables inside,outside, and inbetween. then connect the positive first, then the negative. This is the only way you protect yourself from shock.

[rockfangd]

I also forgot to mention the torque convertor. It doesnt start locking up til closed loop.

187 is a little low but did it get any higher than that?

[Cadillac Jim]

The thermostat starts to open at 180. The ECT should read at least 195 for a running engine that is warmed up.

[Steve Ferraz]

I also forgot to mention the torque convertor. It doesnt start locking up til closed loop.

187 is a little low but did it get any higher than that?

At that time? No, since I only drove for 8 minutes. I'll let you know tonight, I'll be doing some driving that'll take me about 20 minutes. I'll let you know then. I forgot to check about half-hour ago when I got home from work and I am really tired. I know from memory that after driving some time the temp was at 212. Mind you, that was after two to three hours of shopping. lol

[Steve Ferraz]

Just a quick post. After 15 minutes of driving the temp was between 192 and 196.

[winterset]

I'm not sure why, but when the voltage drops while driving, all sorts of strange codes appear and a short affecting the purple data wire is worse. One can go nuts trying to chase these phantom codes down. I would check your wires and connectors. BTW - Has your trunk and gas door ever opened on it's own?

[Steve Ferraz]

Nope. The only electrical issues I have is a faulty Daytime Running Lights (as in it won't turn off when I turn off the engine. So I pulled the fuse.) and as I mentioned in a previous topic that occasionally, when I put the car in park the engine shutdown and the dash is dark except for the PRND (to get an idea what it would look like, turn the key once to the ON position, I believe and the dash would look the same).

Don't have an issue with heating at the moment.

[winterset]

Can your DRL be the twilight sentinel on, and a bad photo sensor on the dash? Do they go off after 5 minutes, or stay on indefinitely?

I'm also wondering if all the codes are caused by a faulty dash cluster. All we need is one bad module in the chain, and is impacts everything. It's like a single bad bulb in a string of christmas lights.

[Steve Ferraz]

Stayed on indefinitely.

[Steve Ferraz]

UPDATE: I'll be wiping the codes again soon but I noticed after half hour driving on the interstate, when I got off and parked the car at the hospital, I noticed a 20 foot trail of fluid leading up to my car.

At first I thought it was my power steering as it was a bit on the low side, but this morning when I got off from work, I popped the hood to check the fluid level in the power steering reservoir, yet it was still full. I was a bit confused until I looked down and saw the tip of the coolant overflow hose was a bit wet. I opened the coolant reservoir and saw it was half empty. Somehow, from driving half an hour on the interstate, the car briefly pumped out coolant. Why?

What would cause the engine to spit out coolant? The car wasn't overheating because the temp once I parked was 196F.

[rockfangd]

maybe it was overfull and purged

[winterset]

That can be normal. I can not even see the fluid in mine unless i use a flashlight and look deep down into the tank. 1/2 full now was probably overfilled before. If it continues, and the cap is old, i would start with a new cap. But try not to replace anything if you can. I overfilled mine the last coolant flush, and i dribbled fluid out the overflow hose. Move the hose so when it drips, it spills onto the ledge of he hvac housing. That way you can tell if it stops.

[Steve Ferraz]

Ok, time for an update.

Last Friday, I went to my mechanic to get my rear brakes replaced and had him check my power steering and see if there was an issue that was causing the engine to purge coolant. Well the good news is that it was just an overflow of coolant and the power steering is just fine. Rear brakes were replaced but I noticed that the rotors and pads are larger then the old ones. The old pads and rotors looked smaller than the front brakes and now the new pads and rotors are the same size as the front (at least just by looking at them).

Also good news is that the P0125, P1605 codes are gone.

Bad news is that I now have 18 error codes PLUS MIL, ABS Light, Traction Control, "SERV STABILITY SYS".

Her are the updated code list (Done properly this time).

PCM P0113 (Must be related to P1605 as it deals with AIC, I believe)

IPC B1552

SDM B1148

SDM B1169

SDM B1160

SDM B1163

SDM U1301

TCS U1301

TCS C1234

TCS C1235

TCS U1255

PZM B2470

PZM B2477

PZM U1301

IRC U1255

RFA U1000

RFA U1305

MMM U1300

Why so many codes? Did the mechanic forget to plug in some brake sensor to get the Traction Control\ABS\SERV STABILITY SYS to come on? One thing for sure, using the scanner to wipe them out does not work.

Help? Seems like I'm digging a deeper hole with this car.

[Cadillac Jim]

I would reset the codes and see what comes back. If part of the wiring harness is disconnected and the mechanic starts the car, say, to bleed the brakes, you will get a lot of codes that aren't accurate once everything is plugged back in.

Another thing that can set a bunch of codes is power-washing, either under the car or under the hood. If it's clean like a new car under the hood or under the car, it's been power-washed. Some mechanics do that before they start on a car to make it easier to work on.