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Sentry Key Immobilizer Module - P1686 code

M

Marcelo73

NAXJA Forum User
Location
Montevideo
I'm facing problems with this module. The Scangauge reports that code error. Sometimes the engine starts and others doesn't.

Is there any way to disable that module? The weird is that some previous owner changed the key, so I'm not sure if the system is still working.

Replacing the PCM is an option?

TIA.
 
^^Exactly correct.

Once the PCM has found the SKIM, you can't get rid of it. So... Remove SKIM, replace PCM in that order. Normal electrical safeties apply...
 
Not to start some isht, but doesn't the sentry provide a pcm input a ground or 12v feed and if it doesn't, that's why it doesn't start? I'd do some research in the fsm wiring diagrams before assuming I'd have to buy another pcm. Yesterday I did a clutch master cylinder replacement in a teal 96 Escort Wagon that a friend had towed to my house last week and I had to remove the battery to get to it. After all back together the car wouldn't start. Maybe the brake fluid leak inside messed up the clutch switch(glad my Jeep doesn't have that)? I bypassed it and it still wouldn't start. I saw under the dash the aftermarket Sentry module with a removable valet key. Removed, re-inserted, still wouldn't start. It's raining and I'm frustrated that this curve-ball is taking up time, so I remove the module and solder the cut starter wire. Car started right up and shifted fine. A pin on the Jeep's pcm is looking for a ground or 12v--figure out which one it is.
 
gradon said:
Not to start some isht, but doesn't the sentry provide a pcm input a ground or 12v feed and if it doesn't, that's why it doesn't start? I'd do some research in the fsm wiring diagrams before assuming I'd have to buy another pcm. Yesterday I did a clutch master cylinder replacement in a teal 96 Escort Wagon that a friend had towed to my house last week and I had to remove the battery to get to it. After all back together the car wouldn't start. Maybe the brake fluid leak inside messed up the clutch switch(glad my Jeep doesn't have that)? I bypassed it and it still wouldn't start. I saw under the dash the aftermarket Sentry module with a removable valet key. Removed, re-inserted, still wouldn't start. It's raining and I'm frustrated that this curve-ball is taking up time, so I remove the module and solder the cut starter wire. Car started right up and shifted fine. A pin on the Jeep's pcm is looking for a ground or 12v--figure out which one it is.
Click to expand...


You mean some of the pins of the 3 connectors that the PCM has?
 
Exactly. The sentry will feed a ground or 12v to one of those wires in the 3 connectors. The Fsm will have a wiring diagram for non-sentry and w/sentry so you can see which wire(s) it interrupts. Once you figure out that, then you can measure yourself when your Jeep decides to start if that wire gets grounded or 12v. Also if it doesn't start, you might find that that wire has no continuity to ground or no 12v.
 
gradon said:
Exactly. The sentry will feed a ground or 12v to one of those wires in the 3 connectors. The Fsm will have a wiring diagram for non-sentry and w/sentry so you can see which wire(s) it interrupts. Once you figure out that, then you can measure yourself when your Jeep decides to start if that wire gets grounded or 12v. Also if it doesn't start, you might find that that wire has no continuity to ground or no 12v.
Click to expand...
nope.

Sentry key fail will cause a start-stall. Cranks, starts and immediately shuts off.

The two modules communicate via data bus and there are no interrupt circuits involved.

Basically key on> SKIM and PCM wake and talk; SKIM says YES! correct key inserted, PCM allows engine to run.
PCM receives a key fault or no message from the SKIM and will not allow engine run.


Marcelo, what year and engine ?
 
Alrighty then. I've never kept a CCD bus Jeep, thus haven't had the joy of experiencing dash failures, no starts, and sentry issues.
 
to add:
P1686 is "no bus message received from SKIM". So either the SKIM is not powered for some reason, like a poor connection, broken wire etc...
 
Digger87xj said:
nope.

Sentry key fail will cause a start-stall. Cranks, starts and immediately shuts off.

The two modules communicate via data bus and there are no interrupt circuits involved.

Basically key on> SKIM and PCM wake and talk; SKIM says YES! correct key inserted, PCM allows engine to run.
PCM receives a key fault or no message from the SKIM and will not allow engine run.


Marcelo, what year and engine ?
Click to expand...

That's is the exactly behaviour: cranks, starts and shut offs. In the console the Security light sensor keep on.

The Cherokee si from 1998 4.0, manual transmmision. In theory was made for export.
The Description I obtained from Chrysler said that and that has SKIM, etc.
The awkward is the keys I'm using seems does not have any transponder. Much less a keyless entry that also says it was built with.


GXWP Keyless Entry w/Immobilizer
GXXP Sentry Key Theft Deterrent System
4YBA Export Option Requirements
6EXP Export Specifications Label
898A LATAM Region



TIA.
 
RKE/security unit is under the overhead console/cover... my be hidden by the headliner a bit. No SKIM in the column for this year. I've seen the terminals corrode on the connector... blueish green powder... if it's there use a toothbrush and some baking soda and water to clean then dry thoroughly.... don't use on the module itselt, just use a small screwdriver blade to lightly scrape the terminal pins.
 
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