Tuning: Low Voltage
Tuning: Low Voltage Well I went to have my car dynoed a couple weeks ago and when they tried writing to the pcm there was not enough voltage at key on to write the program. Its reading right around 10 V at the voltometer on the instrument panel. On top of the battery reading roughly 13V they juiced the hell out of it to try and get the volt reading up and they couldnt. So i ended up taking it home and looking at a bunch of stuff. I checked all the pcm grounds with both a voltometer and a lightbulb test and all grounds were getting 12 V (where they were supposed to with B+ power and 0). Then i checked all the feeds that were going to the Pcm i.e (PCM ignition feed, distributor ignition feed) and all those checked out ok. So then figuring it could have possibly been the voltage regulator built into the pcm i swapped pcm's with a friend just to "key on" and check and see if it was the pcm but it was reading the same voltage right around 10. I also looked for hot wires grounding out but didnt find any and if they were a 12V source they would have blown fuses or melted. Im wondering if anyone has experienced anything similair to this or has any insite. The only other things i can think of is the wire going from the pcm to the obdII port but i cant find the schematics to get to that wire. Anyone have an ideas? Thanks again
-Jeff
-Jeff
You need to leave the charger on the car, its honestly the only way. Does your Fuel pump have the hotwire kit on it or do you also have a elec WP, these will put drains on the electrical system with the key on engine off, such as when you upload the new pcm file.
+1 on the battery. I had a problem couple months back, car would start no prob in the mornings and again when leaving work at 5, but when I stopped at the mailbox to check mail (after a 12 mile drive) it would struggle to start up, I would then drive 1/8 mile to the house and it would start right up.
I replaced the battery and haven't had a problem since.
Sara Lou
I replaced the battery and haven't had a problem since.
Sara Lou
Originally Posted by Formula934
yea the charger was left on the car while they were trying to upload the data onto the pcm. Also, i dont have a fuel pump hot wire kit or an EWP.
When im putting a tune in my car I like to pull the fuses for things that will put a drain on the battery turning the tune. I usually pull the fuse for my fans, and my electric water pump.
I was thinking, unless the charger was hooked up to the ground and positive on the passanger side, the dedicated + & - post, its the only way I could think of circumventing the battery
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Have some one check the voltage on your battery while you put it under a strain. The best way to put it under a strain is to bump your starter while blowing your horn. If it doesn't have close to 12v then I think you battery is toast.
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Verdad Gallardo yea im thinking the problem is more complicated than that. The battery is a brand new interstate. I replaced the old battery thinking that was the problem but its definately drawing voltage somewhere and the only place i really havnt checked is the wire going to the obdII?? Im really stumped on this one and like i said the little things like the battery etc. have been checked out and are ok.
