Ram Promaster Forum banner

1 - 20 of 26 Posts

·
Registered
Joined
·
47 Posts
Discussion Starter #1
So this is a new one, I go out in the morning and start the truck, it runs 3 sec and dies, 4 tries and then it will run, three weeks earlier I go out and turn the key and it cranks and cranks and cranks, no start, then I waited a few minutes and it started, any of this sound familiar to anybody, I cant understand the problem.
 

·
Registered
Joined
·
47 Posts
Discussion Starter #5
I tried my back up key fob and it worked today. So I hope this is it. Is there a way to repair the old ones?
 

·
Registered
Joined
·
893 Posts
Most mechanics would say "that sounds like a fuel pressure problem". I would say that, except that in over 5 years on this board I've never noticed someone having any kind of problem whatsoever with the fuel pump or fuel pressure regulator. Not once. Still, that's likely what a mechanic would test first. There's a shrader valve on the fuel rail where he can plug in a gauge. That's IF you can get it to consistently reproduce the problem.

The very first step would be to read the codes - not just the generic codes that light the light (is the light on?) but the manufacturer codes, which require a pro scan tool generally. The computer may know much about what's going on, including freeze frame data when the problem occurs.

If I had to take a wild guess, I'm guessing that there is no mechanical problem with the truck. Somewhere there is an intermittent wiring issue, and it's giving the computer a false reading of some kind. And it's close to the engine, because from your description the problem goes away once it starts and dies a few times. Right when the thing starts, much of the engine function is running off open loop/startup settings, which are immutable in the ecu. Once it initially starts, then the computer starts gathering info, and something is making it die at that point. That's my guess anyway, a complete guess I should add.

Step 1 is to gather some symptoms. Does it do it always. Is it consistent and predictable. Is anything else happening when it happens.

Step 2 would be to get it to a shop and look for codes. Since it's fairly new, it's going to have to be a dealer or a high volume shop, as a smaller shop probably won't have ponied up the money for the latest version of the scanner software on a vehicle that's still under warranty for most people. A phone call to each shop asking if he can read all the codes on a 2017 will narrow it down.

If you have to go to the dealer, brace yourself for a hassle. They will be unlikely simply take 3 minutes and walk out to the parking lot with a scanner and read the codes. Instead they will make you wait 2 weeks for an appointment, and then have it for 3 days while they "get to it". I hate that. But without knowing what the computer thinks, you can throw parts at it all day long and go broke guessing.
 

·
Registered
Joined
·
47 Posts
Discussion Starter #7
Waiting to get it in, its strange problem. I read somewhere the fact that it starts and runs for 4 seconds means the key fob has a bad battery. Anyone hear of this, in the mean time I will be getting it in to see what the wizards at dodge will tell me.
Oh and yes changed the battery. Same problem .
 

·
Registered
Joined
·
893 Posts
Possible, but it seems sketchy. If it’s a security issue, why isnt the light lit (theres an idiot light for security)? And, what is the advantage in programming it to run for 4 sec and die, when if it’s a key issue you’d just program it to not start.

And it’s not battery related, or else the fob wouldnt unlock the doors.
 

·
Registered
Joined
·
3,218 Posts
If one key works and the other is hit and miss, it seems to me the transponder in the hit and miss key is having a problem, no battery required.

That's the way I understand it, could be wrong.
 

·
Registered
Joined
·
47 Posts
Discussion Starter #10
Ok, here is the update, I put new duracell batteries fresh from HD in the two fobs, so far it has not had any problems starting. Lets see if this holds up. I did put what I thought were new batteries in them that I had in my office, but they must have been old, I could lock and unlock, but this might be it. I will keep posting if this is not the problem, but so far so good, I cant remember where I read the post about the battery in the fob causing this , but it was clear, it said the engine would start and die after 3 or 4 seconds. This was what was happening.
 

·
Registered
Joined
·
3,218 Posts

·
Registered
Joined
·
438 Posts
My key fob doesn't work at all, and my spare key is not a remote, so I don't see how batteries in the key fob can make a difference
 

·
Registered
Joined
·
1,322 Posts
The new batteries have solved the problem, I cant understand it either.
The sentry key antenna is most likely the cause. The battery in the key fob has nothing to do with the RF chip in the fob. Most likely in your frustration you banged, wiggled and jiggled the ignition and it is now working.

The Sentry Key Immobilizer System (BCM) control circuitry integral to the Body Control Module (BCM) includes a Radio Frequency (RF) transceiver. The BCM circuitry transmits RF signals to, and receives RF signals from the Sentry Key transponder through the tuned Sentry Key antenna enclosed within the molded plastic antenna housing. If this antenna is not mounted properly around the ignition lock cylinder housing, communication problems between the BCM control circuitry and the transponder may arise. These communication problems will result in Sentry Key transponder-related faults.

When the ignition switch is On, the BCM control circuitry transmits an RF signal to the transponder in the ignition key. The BCM then waits for an RF signal response from the transponder. If the response received identifies the key as valid, the BCM control circuitry sends a valid key message to the Powertrain Control Module (PCM) over the Controller Area Network (CAN) data bus. If the response received identifies the key as invalid, or if no response is received from the key transponder, the BCM sends an electronic invalid key message to the PCM. The PCM will enable or disable engine operation based upon the status of the BCM messages. It is important to note that the default condition in the PCM is an invalid key; therefore, if no message is received from the BCM by the PCM, the engine will be disabled and the vehicle immobilized after two seconds of running.

The BCM performs a self-test each time the ignition switch is turned to the On position, and will store fault information in the form of a Diagnostic Trouble Code (DTC) in BCM memory if a system malfunction is detected. The Sentry Key antenna can be diagnosed, and any stored DTC can be retrieved using a diagnostic scan tool. Refer to the appropriate diagnostic information.
 

·
Registered
Joined
·
1,322 Posts
If you have other RF chipped devices on your key ring they may interfere with the SKIS. The 99 Jeep had that problem with Mobil pass There was a tsb for that.
 

·
Registered
Joined
·
1,322 Posts
After some after thought, the act of changing the battery could have fixed your problem. The RF chip is on the circuit board in the fob not in the metal key, so by opening the battery door you could have moved some debris that may have been on the RF chip. Just an after thought as to why changing the battery may have solved the problem.
 

·
Registered
Joined
·
1,982 Posts
If it needs batteries to operate,.......then why wouldn't it simply stop working if the batteries died and work again with new batteries?
 

·
Registered
Joined
·
1,322 Posts
If it needs batteries to operate,.......then why wouldn't it simply stop working if the batteries died and work again with new batteries?
The RF chip does not need a battery. A RF chip gets its power from radio waves.
 
1 - 20 of 26 Posts
Top