Reading up on that one, less than 10.5 volts to the PCM or battery disconnected can set it. You might have to test power at the PCM to see if it's dropping out or getting too low assuming power is fine elsewhere.

 

Ok thanks. Battery has definitely been disconnected but when i clear the code it comes back after approx 20 seconds of idling.

Do you happen to know where I can check for voltage on the PCM? harness location and pin number#?

Had this code last year and parked the Car for the canadian winter. I was planning on getting this code cleared before re-insuring car and getting e-test as its over due. IS this a code that requires some mileage put on the car before it will truly be gone?

Thanks Sailor!

 

Don't have the pin out handy (by the way it's 10.5 volts, I see the 0 didn't get in the typing and edited that).

I'd actually look at the small ground wire to the battery for the PCM first, just because poor contact there is a common cause of multiple issues. When ground is lost the odo will come up with dashes and the car won't run, maybe poor connection can drop voltage enough by resistance to set that code.

 

I have never seen dashes on the odometer (other than when I was applying a new tune).

 

No amount of mileage will clear P1633. The keep alive memory circuit must see at least 10.5V, according to Ford. Sounds like you have a hard fault - weak connection or intermittent.

Check all the connections from the battery terminals, not just the big post terminals.

You could also try unplugging the main PCM connector and then simply plugging it in again to attempt to clear any possible corrosion.

Edit: What sailor just said.

 

thanks guys,

10.5 volts does sound more familiar from the little bit of research I've done.

I know the voltage dropped 10.8 volts at start up (according to my SCT x4 datalog) but I'll assume that's at the battery. And goes to 14V ish when running. Replaced the battery with an Optima yellow top recently so those terminals are clean. Ill clean up the cable leads soon, but they weren't too dirty (but they weren't exactly spotless either).

The PCM... Is that the board in the passenger side area, under the glove box? and is the main connector hidden in that area somewhere or is it in the engine bay?

And just want to say again the car runs fine. No rough idle.

 

The PCM is behind the passenger side foot well kick panel (just ahead of the inertia fuel shutoff switch). Before you go digging around there though, I'd make sure the battery connections are spotless first. No need to possibly make more trouble.

 

Grab battery terminals and try to twist them by hand. If the OEM terminals then cleaning posts off really clean can remove enough material that the terminal seems tight by the bolt when it's not, it will twist by hand. Unacceptable. The OEM terminals really suck there.

 

So I just cleaned up the battery leads and cleaned the corrosion off of the cables and cleaned the grounds that were close to the battery. No luck. Started fine as per usual but the code came back after about 20 seconds.

Voltage dropped to about 10.8 v at start up again. (According to the SCT x4)

Any other ideas? Could I just run an independent cable with an inline fuse to the PCM?