Code question

[British Slave]

I guess I'm suffering from brain lock, but on an 87 with 350 TBI, is it normal to be able to disconnect a sensor, get the SES light and when the sensor is reconnected for the SES light to go out? No code is stored.

 

[mudbuggy]

How I understand obd1, a code can only be retrieved if the ses light is on

 

[British Slave]

I guess my question should have been ; Is the SES light auto reset, as in when the problem is corrected it resets?

 

[4X4HIGH]

I guess my question should have been ; Is the SES light auto reset, as in when the problem is corrected it resets?

Yes, in fact the only time the SES light will come on is if there's a "hard code" created.

 

[Jessie James]

That does not sound right. You're saying you jump the A & B terminals of the data port after you've stopped the truck, and there are no codes other than "12" (which indicates you are in diagnostic mode)?

 

[British Slave]

That does not sound right. You're saying you jump the A & B terminals of the data port after you've stopped the truck, and there are no codes other than "12" (which indicates you are in diagnostic mode)?

I can unplug the temp sensor and the SES light will come on, , reconnect the sensor and the SES light will go off. I noticed this happening while timing the engine. When I unplugged the timing wire, the light comes on, plug it back in the light goes off. And yes, the only code is 12.

 

[4X4HIGH]

I can unplug the temp sensor and the SES light will come on, , reconnect the sensor and the SES light will go off. I noticed this happening while timing the engine. When I unplugged the timing wire, the light comes on, plug it back in the light goes off. And yes, the only code is 12.

Something is wrong then because when you disconnect the EST wire it will store a code 42 and it will stay for a given number of starts before it goes away on it's own (assuming there isn't a problem) or you clear the code(s).

 

[mudbuggy]

Hard codes store in memory, could have ses light on, but if the problem corrects then the ses will go out. A soft code turns on ses, but doesn't store in memory
I normally get my ses light to trun on once a week when its cold out 33. Egr not operating correct, (don't remember exact definition) but another sensor is picking up that the egr is not cycling correct. Something is 'bothering' its operations. Carbon is stuck in the orfice not allowing it to close but once the blockage self clears then the light goes out. No codes in memory