I installed my 791xv 2 years ago or so, but recently i changed the computer in my car from the Geforce ecu, back to stock, now whenever i remote start the car it starts up but drops immediatly and when i try to relearn tach it wont flash blue. Anything that can be done ? It won't even stay running if i start the car, press the * twice, and remove the key it just shuts off once the key is removed from the ignition. The lights flash as if it were gonna work but it doesnt.

 

Where did you tap? Whats the voltage the wire is reading?

 

green white @ ecu. I soldered connection i know its ok.

 

im not familiar with the process on tach learn on the 791's, but perhaps check your other connections that have to do with learning the tach (during programming)?

...ie: I have to hold brake while the tach learns on my units. If the brake line is disconnected for whatever reason, obviously the programming wont work..


Other that, confirm you have a tach signal at the brain

 

yea its all there, the only thing i can think of, is the rpm switch for the variable intake is hooked up to the same tach signal @ the ecu. Maybe thats throwing it off ?

 

cut it and rule it out.

 

i did still didnt work lol, im stumped.

 

bad brain?

 

check fuses in the brain. I have a compustar and it was acting weird. I took it in and from the problems I was describing, the installer thought it might be a bad brain. He checked the fuses and one was no good.

I don't know anything about your system, but that is something that I think could get overlooked.
goodluck
hope that helps.

 

the tach signal doesn't run through a fuse.

 

im gonna unplug the main harness for a bit, even though i know the dei alarms store the info even if there unplugged :\

 

if it turns out to be the brain, run it tachless. If your car is in decent shape you should be okay.

cheaper than getting a new one..

 

might just toss in the towel an dgetthe 5900 sst its all plug n play i think isnt it ?

 

Had the same issue months back when I threw in my UTEC, went tachless and never had a problem since.

 

hmm ill swithc over to voltage sense and give it a shot.