I have a 95 Blazer lt, and lately the engine light has been coming on, truck is running fine, no problems, but today i got curious when the light came on so i went into the local autoparts store and the guy came out and plugged in his obd2 scan tool into it and could not access the codes, actually the code reader wouldn't communicate with the truck. so i went up to the local tire shop and a tech came out and tried to scan the engine light aswell but no luck, his scan tool (snap on) wouldnt communicate either.. could i have a bad ecu,? is there anything i can be checking, as i said before the truck runs great, trans however is not that great... but ya, any help on this subject would be much appreciated.

 

'95 is OBD I and many OBD II readers will not communicate with it. Probably nothing wrong with your 'ecu'.
Use the paper clip technique to retrieve the codes. Search or post again if you need more instructions.

 

95 was a changeover year, it could have OBDI, OBDI.5 or OBDII depending on when it was built. Find a qualified driveability tech and he will know how to identify which system you have and retrieve the DTC's. If the OBDII scan tool plugged in properly but did not communicate, you probably have OBDI.5

 

Correction, some very early 95's are OBD1 while the vast majority are really neither OBD1 or OBD2, but a mix of both.

If it was one of the expensive snap-on scan tools, then it should work. If the scan tools are not communicating with the truck, I would first start by checking the cigarette lighter fuse. It also powers the DLC (diagnostic link connector).

 

cigarette lighter fuse checked out ok.. never heard of obd1.5 .... yes it was a expensive snap on one, it was the modis.... i did find power at the obd connecter, but still wont communicate. i purchased a gm code reader from the local parts place, still no go, i am wondering if the ecu is faulty.... any other suggestions?

 

Possibly a faulty ECU, but you really do need to make sure that the scanner is compatible with this in-between ECU.