I have a 99 F-150 5.4, 4x4 I am trying to help a friend out with. It is bucking missing and stalling. Hooked up scanner and got a crank sensor code. Changed it out and after taking it for a test ride got a P1636 - Inductive Signature Chip Communication .

Has anyone ever incountered this ? It seems as though it's a pats system fault ??????

 

PLEASE and Thankyou in advance

 

The PCM has lost communications with a special chip/device that looks at operating inductive signitures from hardware such as coils, solenoids and relays.
What that means in another way is it looks at the current and voltage 'wave form' and is programmed to expect a certain shape and time constant.
Usually indicates the PCM is faulty and would need replacement.
It's an internal fault.
Good luck.

 

Thanks Bluegrass 7. When I first checked this thing out I did not get any codes. Then after driving it for awhile I got the code for a crank sensor. I replaced the crank sensor. Went on test drive then got the 1636 . Could the PCM be throwing false codes ? Due to it being faulty ?

 

Anything is possible with an internal problem.
Clear the codes and see what comes back.
If it keeps repeating, it suggest that any attempt to read inductive signitures will generate a code even if there is no problem with the part.
The chip that does this will fail everytime it is supposed to read a signiture.
You may even get away with it causing no drivability issues until a 'real' fault with say a trans shift solenoid occurs, then you may not be able to ID the trouble due to the faulty chip .
Then you have two problems.
.
To expand on this, the PCM uses this chip to tell if......
1. an action has occured ok.
2. was it to slow?
3. is the winding shorted?
4. is the winding open?
5. is the operation stuck etc
6. any external issue in the harness such as a short to ground or a cross to battery.
It does all these things by analysis of the operational signiture expected for the part and action requested.
The device is at a 'chip level' because it's composed of a lot of circuits that do different things as mentioned above and report to them to the main PCM program via a 'bus'.
The 1636 says that 'bus' is open.
.
A more simple example is the power window operation as monitored by the GEM. The motor hardware has no up or down stop switches so how does it know when to stop powering the motor? Ans, by the increase in current when the window is fully either up or down against travel limits, the GEM reacts instantly to a rise in current draw of the motor and opens the relay.
This is in part to keep children from getting their heads/neck/hands etc caught when fooling around with the window closing switches and backed up by a driver cut- off switch on the arm rest when there is a chance of an incedent.
I can't stress enough how much computer control there is and how many owners are unaware of that level and think things are so much simpler than it really is.

Hope this makes some sense.
Good luck.

 

I have an 03 computer that was only in my truck for 10,000 miles if you think you might be able to use it, let me know.

 

Thanks Bluegrass you're really a big help. I will have to monitor it some more to see what it comes up with next. If I were to get a known good used PCM would it have to be programed by Ford or is it plug & play ?

 

The PCM will need to be flashed if replaced.

 

If you have PATS it will need to be programmed for that function and 2 keys at the least.
The dash gets in on the act as well.
Best for the dealer to program from the 'as built' data base then you have the OEM program complete with specific options.
Good luck.