SES light and loss of low end power?

[Kalgorn]

This just happened to me today. Once in a while when I start my car in the morning and the "low coolant" light will light up. Once I back out of my spot the light goes away though so I never think too much of it. The coolant is probably a tad low but I figure if the light goes away and doesn't come back on at all until the next morning at startup, it can't be deathly low.

 

I've experienced an SES light in the past once in a while. The light will just randomly come on and usually lasts until I turn the car off but sometimes it just goes away. It doesn't happen very often. The last time was quite a while ago.

 

However, today I was driving home from school and the light came on. Like usual (I know, I'm a douche bag) I just ignored it since it's done it before and I came to a red light. When the light turned green and I pressed the gas, it was barely accelerating. But once I'm up to about 10mph it's fine. It did it again at the next light too and then I was back to my apartment.

 

Any ideas what this could be? I've got no way to read the codes either (and don't know how anyway).

[JoroCorona]

Intake Manifold Gasket?

[digitaloutsider]

The LC light is a common problem having to do with the shitty sending unit GM had. Checking your codes on OBD-I has been discussed millions of times, including in the W-body FAQ's. Read.

 

Edit: What the FUCK happened to my FAQ's..?

[Kalgorn]

But could it be the gasket if I drove the car back to school today and it ran perfectly fine? The low coolant light didn't come on but I think that's because it's not brutally cold in the afternoon.

[slick]

Straight from w-body.com:

In every GM W-Body car, there is a computer that controls virtually all aspects of the engine's operation. This computer is called the ECM, or "Electronic Control Module". The ECM is constantly controlling, adjusting, and monitoring engine conditions. If there is an engine malfunction caused or detected by any one of the many sensors connected to the ECM, a trouble code will be stored in NVM, or Non-Volatile Memory. What you need to do first is find out what trouble codes are presently stored in the ECM. You can read these trouble codes in several different ways. The best and easiest way is to purchase a "scan tool". A scan tool displays trouble codes numerically on a LCD display or computer terminal. The more expensive scan tools also display the details behind the trouble code in full detail, such as the sensor voltage detected and what it should be. The drawbacks to the scan tool method is that a scan tool costs several thousands of dollars. The other method is to perform a "NON-SCAN" diagnostic circuit check by having the "Service Engine Soon" light blink out the codes stored in the ECM.

 

Regardless of the method used, the secret to communicating with the car's computer is through the ALDL connector (Assembly Line Diagnostic Link). This is where a scan tool would plug in. We will also utilize this connector for our "NON-SCAN" method.

 

NOTE: The cheap $25-30 "scan tool" and the $5 "scan key" that you find at many auto parts stores are NOT actual scan tools. They are essentially expensive jumper wires. Don't buy them unless you like wasting money, a paperclip or wire will work.

 

The following "NON-SCAN" method can be used to read these codes.

 

A steady "Service Engine Soon" light with ignition "ON" and engine stopped confirms battery and ignition voltage to the ECM.

 

First you must locate the ALDL connector which is located under the dash on the driver's side, to the right of the steering column.

 

The ALDL connector looks like this

 

For reference, ALDL pinouts are: A. Ground; B. Diagnostic Terminal; C. A.I.R. (if used); D. Service Engine Soon Light (if used); E. Serial Data; F. TCC (if used); G. Fuel Pump (if used); M. Serial Data (if used)

Use a jumper (paper clip) and connect terminal "B" to terminal "A". Terminal "A" is the ground connection. Turn the ignition "ON", but don't start the engine, it must be left NOT RUNNING.

The ECM will cause the "Service Engine Soon" light to flash Code 12 three (3) times consecutively. This would be the following flash sequence: "flash, pause, flash-flash, long pause, flash, pause, flash-flash, long pause, flash, pause, flash-flash" (See Figure 1). Code 12 means the diagnostic system is operating properly. Following Code 12, the other trouble codes will be output if present, or Code 12 will be output continuously if no other codes are stored. If more than one code was stored, they will be output from lowest to highest, with each one being displayed three times.

 

Example: An error Code 25 will be: 12,12,12,25,25,25,12,12,12, etc.

 

 

 

 

 

 

Figure 1: Example of "Service Engine Soon" light flashing Code 12 continuously.

To quit scanning for codes, simply shut the ignition "OFF" and remove the jumper.

To clear codes, ensure that the ignition is "OFF". Depending on the car, you can disconnect an inline "pigtail" fuse at the positive battery terminal, or remove the ECM fuse in the fuse block. Power to the ECM must be disconnected for at least thirty (30) seconds. This will cause the ECM to reset clearing all Codes, and the ECM will now need to re-learn driving parameters.

[supreme_style21]

Yeah check the codes before you do anything.

 

When you say it would barely accelerate, was it stuttering/choking/missing/cutting out/bog down?

[EurosportZ34]

SES light and loss of low end power?

 

 

hrmmm....sounds like a 3.4

[Kalgorn]

Yeah check the codes before you do anything.

 

When you say it would barely accelerate, was it stuttering/choking/missing/cutting out/bog down?

 

Not at all. It just didn't have any power. I didn't want to get on it hard either because I wasn't sure what was wrong with it. The RPMs were raising very slow from a stop.

[JoroCorona]

Get us those engine codes and we can help Kal. We're kinda grasping at nothing at the moment.

[Kalgorn]

I plan to get the codes very soon. What exactly do the other codes look like? I'm assuming they're also a series of blinks? Or am I wrong? Sorry... never had to do anything like this on a car and I don't know as much as I wish I did.