chrisz71

how do i check for a bad ecm without a scanner?

Jkevin

Borrowed from another forum:

One quick check is to watch the MIL lamp before you turn the key. Insert the key and turn it to RUN, not START. The MIL lamp should turn on briefly, then off briefly, then back on continuously. This flash alerts you that the ECM has passed power up diagnostics and has a valid PROM and/or CALPK installed. If you don't get teh flash, there is something wrong with the ECM.
Another thing you can do is to insert a 3,900 ohm resistor between terminals 'A' and 'B' of the ALDL. This forces the ECM into Backup Fuel / Factory Diagnostics Mode, or Mode 1. This will force the ECM to use the lookup tables in the PROM for base fuel and spark curves.

You can try to force Mode 2, which is an I/O excersize. If the resistor is in place, and the transmission is in PARK/NEUTRAL or the clutch is depressed when teh key is turned to RUN, you should be able to force Mode 2. This will force the ECM to scan for loads and inputs, then excersize the discrete outputs at about a 32Hz rate. You shoudl hear the fuel pump realy buzzing rapidly, then teh IAC stepping, then the injectors clicking open and shut, etc. If this is working, the ECM shoudl at least be able to operate the engine in Backup Fuel (Limp Home) mode. If this doesn't work, your ECM may have an I/O problem.

tech2

that information was borrowed from a site that has no relevance to an obdII diagnostic platform. don't do any of that. Bcm codes will not set off the mil light, only powertrain codes do that.

Describe the symptoms, not what you think the fix is and post any body codes that have set. you will need a full function scan tool to read body codes.