ecm "safe mode"

[stockgp]

anyone heard of this?

 

i'm trying to tell a guy on another forum how to do an idle relearn and one of tyhe other members is insisting the computer is in safe mode

[3pt1lumina]

wtf? never heard of it. A car's computer never goes into "safe mode" as far as I know. Isn't that only for like house computers?

[Prospeeder]

you mean like Open loop? Thats the only thing i could think of, i really dont think theres a "safe mode", whats his car doing, the usual crap an idle relarn would help? What is it?

[stockgp]

he rebuilt his top end and it's stumbling and trying to stall when slowing or stopping.

 

typical idle relearn crap

[3pt1lumina]

sounds like an idle relearn to me

[stockgp]

oh and also he was wondering why a couple of his dic options won't reset and keep beeping. i think it was oil/filter and tune-up reminders.

[Hairdo12]

I have heard of ecm "limp" mode, but have no clue what it is.

[stockgp]

[Prospeeder]

oh and also he was wondering why a couple of his dic options won't reset and keep beeping. i think it was oil/filter and tune-up reminders.

 

Make sure hes holding the reset button AFTER all the text for the specific thing scrolls through and stops, or it will just ay Missing Op.

[stockgp]

yeah i already told him that. it took me forever to figure mine out, too

[Prospeeder]

seriously,i had my car for like 4 months before i figured that out, i actually had to ask on here

[DaveFromColorado]

Yes, there is a "safe" mode, or "limp" mode as it's called. IIRC - it's not built into the chip itself, it's built into the controller board the chip is soldered to to make up the whole PROM and aftermarket units won't usually have this.

 

It also goes into this mode when you run the jumper across the two terminals on the OBD-I port same way as if you are checking for codes.

 

in this mode it will run the engine really fat (tons of fuel) with the timing way back, and have the fans on the whole time, and on the the electronic trani's it will run 'em in 2nd gear pretty much the whole time - if you really think this is his problem, have him change the whole computer, not just the chip, because there's a reason the part failed and those computer controls can get pretty sensative.

 

--Dave.

[stockgp]

oh i found it in alldata. it's called "limp home fuel mode."

[gp90se]

I don't know much about GM programming, but with a dodge ECU, as dave said, will keep the car in such a manor that it runs without killing itself, fuel is dumped into the motor, timing pulled, open loop, 2ed gear only, rad fans running, egr off and I think a few other things. Clean the IAC, disconnect the battery, turn the key for 10 seconds, put the battery back on, start it and take it for a drive on the highway.