View Full Version : 97 concours service engine soon no codes

12-11-04, 12:33 PM
have a 97 concours. started running rough, idling lower than normal, and then today the service engine light came on. when i checked the codes there where no codes displaying current. can anybody help me with this problem? :confused:

12-11-04, 05:09 PM
Could be a bad spark plug or wire, partially plugged fuel filter, etc.

Any codes in history?

12-11-04, 05:59 PM
i cleared the history the day before because of a traction problem, so there is no codes in history. Yesterday the dealer told me there was a recall on the fuel rail, and installed a new one. could this have something to do with it?

12-11-04, 08:29 PM
If the service soon light is on there has to be a code.....check it again. If you turn the engine off and then turn the key on to check the codes any code in there will usually revert to a history code until the next engine run event. Any code is important potentially whether it is history or not. If the check engine light is on then check the codes before you turn the engine off. Checking the diagnostics while the engine is runnning is fine.

If this just started when the fuel rail was replaced I would beat tracks back to the dealer where the work was performed......

12-11-04, 08:52 PM
It seems like everyone who has the fuel rail replaced ends up having the same problem. Same thing happened to me. My money is on the plug wires.

12-11-04, 09:06 PM
That is the very reason I tell people to leave it alone if it is running OK. Most spark plug wires are fine until disturbed and then the wires are broken or a terminal is pulled off inside the boot or a boot is torn in the haste to remove the wires to beat the clock....

I saw a large box of spark plugs at a Detroit dealer several years ago. Seems all the mechanics tossed the old plugs they removed from engines into the box over many years and we found it during a meeting of some of the service people. They brought out the box (it was about the size of a large shoe box and almost full) to show us how "bad" the plugs were because of how many had been replaced. Most of the plugs were fine (one fouled plug means all 8 get changed...) and there were some fouled and cracked plugs but the interesting thing was that one plug in 20 had the spark plug wire terminal still attached to it. Not the boot...just the small metal terminal that clips to the plug tip and is crimped to the wire..or WAS crimped to the wire. This will commonly happen when the mechanic grabs the wire it self and tugs rather then pull by the boot. In any case, one in 20 plugs went out went out the door with no terminal connecting it to the wire. It will run fine at first then the center conductor of the wire will burn out from the arcing and the plug wire will be "bad"....

Even being carefull it is pretty easy to damage a spark plug cable..especially one that has laid there un-molested for 5 or 6 years...by simply removing it from the plug so it is best to just leave them alone until plugs/wires are definitely needed and/or they have so many miles/years on them so as to have completely served their usefulness.

12-12-04, 10:06 AM
I just checked codes again. pcm p1380 current is showing. If i'm correct that means misfire. thanks for everyones help.

12-12-04, 11:16 AM
Yup, that means misfire, but P0300 is also set, and that's why your SES light is on. From the service manual:

DTC P1380 ABS DTC Rough Road Data Unstable

Circuit Description

This diagnostic DTC is used to determine when the EBTCM has lost the ability to provide rough road data to the PCM for misfire detection (DTC P0300). When the PCM sees this condition is present via serial data, DTC P1380 will set.

Conditions for Setting the DTC

Test Conditions
Engine speed 7969 RPM or less
Engine load 79.7% or less
DTC P0300 is set and requesting the MIL ON

Failure Condition
Rough road indicator not being sent by EBTCM.

Action Taken When the DTC Sets
The Malfunction INdicator Lamp (MIL) will not illuminate
No message will be displayed

Conditions for clearing the DTC
A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
PCM battery voltage is interrupted.
Using a Scan tool.

Diagnostic Aids

If this DTC is set along with DTC P0300, it may represent an invalid misfire due to a loss of rough road data.
Several ABS system problems could cause a loss of rough road indication from the EBTCM. All ABS/TCS system problems at DTCs should be corrected first. Then duplicate the conditions under which DTC P1380 set and see if the problem reoccurs.

*** So, it looks like there may be some other code set in the RSS or TCS system that's causing the loss of rough road data. Look for codes in that area. The P0300 is why the light is on, according to this, so something else is causing the misfire. That could be any number of things, and if it started BEFORE you got the fuel rail replaced, look in the common and simple areas first: plugs, wires, fuel filter, etc. Go through the codes carefully. There are other codes there, I promise. Those will help diagnose the problem. Check out the info from this link and hopefully something here will help:


Let us know what you find...


12-12-04, 02:31 PM
just took it for a drive. pcm p0300, acm b1348, and msm b2119 are all showing. no tcs codes. before i cleared the codes the other day for the traction situation tcs c1232 was showing.

12-12-04, 03:55 PM
OK, here we go:

B1348 - Very Low A/C Refrigerant Pressure
B2119 - Lumbar Forward/Aft Sensor Failed
C1232 - Left Front Wheel Speed Circuit Open or Shorted

This is what I think:

** The A/C system has a leak
** The A/C system is low on refrigerant for some other reason
** The pressure switch on the A/C system is bad or disconnected

** The power seat has a problem that I've never seen or heard of before

** The speed sensor in the wheel bearing is bad and needs replaced
** The wiring for the speed sensor is cut or disconnected

Bottom line:

The P0300 is the misfire detected code and the reason why the SES light is on. The misfire is probably plugs and/or wires, but you've not mentioned how many miles are on the car. It could also be a fuel filter, a coil, FPR, fuel pump, IAC, etc. The throttle body bore and blade probably need to be cleaned. When does the misfire/hesitation happen? Only under acceleration? Only at idle? Only at cruising speed? Only on alternate Thursdays between 1:14 and 2:37 AM in towns that start with the letter C? All the time? That will help narrow it down and determine a root cause, then you can get it fixed. Let us know.