Okay, odd question for you EFI savvy guys out there. Viper, I'm looking seriously at you to be the man on this one.

Let's say I'm at the salvage yard and spot what appears to be a pretty clean EFI motor. Maybe I pull the heads and pan and everything looks great, but I really want to know how many miles might be on this motor.

So, I'm thinking to myself "Is there any way you can think of that I can apply power to the PCM in order to read the odometer for mileage?" Keep in mind, there are no batteries in the salvage yard cars (would be looking to bring my own battery pack in with me) and wiring harnesses will likely be butchered.

So, what voltage of battery pack would I need to bring; what pin on the PCM do I need to apply power to; and what pins on the PCM and dash display harness do I need to wire together to be able to read the odo?

I hope there isn't a really simple answer to this.

OBDI ECM's don't keep track of miles. '96 and later vehicles do (probably in the body ECM, not engine ECM) but I don't know if it's possible to pull that info without a real ($$$) scantool.

How do the OBDI vehicles with digital odo's store the data? My '93 Bronco had the digital and I always assumed it was the ECM that was telling it what to store.

you need to power up the instrument panel. If you ever had to replace one from the Dealer, they would send in current mileage and the new one will come with mileage pre set before showing up.

That certainly sounds much easier than trying to power the ECM and then wiring the gauge clusters.

if the harness is still there, just hook up battery as normal, then drop the actual ignition switch from the column and slide the lever to power up. You could even see if anything else works, listen to the radio, have a party...who knows?

Bring a jump pack if you have one available. If you can get power to the system, many cars & trucks will turn on the odometer by pushing the trip reset button (if it has one).

Chad

I dont know about all yards, but the last time I was looking at some seats I wanted, I needed power and I asked the front desk, they told me if I need power I can ask them and they have ones to use to power up the car to move things like that. They may even be able to find out the mileage on the vehicle when it was brought in. Depending on if they are in a nice mood or not.

You can power up with a small 9 volt as well. I use a 9 volt batt. to save memory on cars when changing batteries.