Viper remote start turns over but wont start

Hey Gents.

I lack knowledge of the engine itself, thus I ask for your input.

Engine starts normally when key is used to ignite. However, when I try to use the remote start on my key fab it turns over but will not start the engine.

If start the engine with my key, then turn it off, wait a few seconds the remote start works.

They remote start has worked flawlessly for 7+ years even in the Colorado winters, suddenly now, its not.

My only thought is the spark plugs may be coming to the end of their life ~approximately 42k miles. No check engine light, Fuel adequate, no door ajar indicators, no battery indicator. Unknown viper head unit model, Key fab model 7654V.

Appreciate any advice

 

You need to see if the security light is flashing on the dash when starting.
If it is, then the transponder chip isn’t communicating with the ECM.
When this happens, you can crank the truck all day. Or until the battery dies.
But the truck won’t start.

 

The receiver does not flash when starting.

 

This light does not flash when starting?

 

Not the plugs. You'd have the same issue regardless of starting method.

I don't have a remote anything but I wonder if there's a security issue you're dealing with. I'm guessing your key has a chip..perhaps the battery is weak in the fob and it's not reaching the truck like before.

Key vs key but to give an idea, my wife's Rav4 starts fine with her key. I got a key cut (non-chipped) for my keyring in case she locks herself out that will open the doors. It will crank but not start the engine.

 

The key has to be really close to the ignition, The ignition actually "powers" the chip in the kay.
Kind of like a wireless charger works.
It would be nice know how the remote start utilizes the transponder ID.
Is it a stand alone system with a generator? Or a hidden chip close to the ignition?

 

@TnShooter I see. That light flashes persistently. Locked, unlocked, while starting, even just sitting there.. its always flashing.

 

Then that means the Transponder ECU isn't seeing the key. Or what ever the Remote Start uses to generate a "Key Signal".

 

Good question, I have no experience with remote start of any kind so I'm gonna let you run with this one.

 

I don't either.
But I fooled around with my key to see what happens if it doesn't see a signal.

 

Still one up on me as I can't get to my wife's Rav4 presently

 

That has me confused. I dont understand how it can start the car remotely 30 sec after starting it with the key if the transponder doesn't see they key.

Regardless do you know of a fix?

 

Some modules don't go to sleep right away.
Some take 15-30 mins to go to sleep.
Maybe that's why it start with the fob 30 secs after using the key?

Do you know what model remote start is installed in the truck?

 

Damn I wish I did. I tried finding the main unit model sometime ago but was ultimately defeated, I never found a model number on the box. I had it installed years ago, I wouldn't even know where to look. I appreciate your help brother.

 

All I know to do is look under the dash for wires that "Don't belong". See if you can find the remote start box and see if there is an internal battery or something?

 

Yea really need to see what kind of remote start you have and how it "bypasses" the immobilizer.

 

can you explain what the immobilizer is?

 

Simple Explanation

The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ECU that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the transponder key ECU sends a signal to the ECM to prohibit fuel delivery and ignition, effectively disabling the engine.

Long Explanation

When the transponder key ECU detects that the unlock warning switch is ON, the ECU provides current to the transponder key coil and produces a faint electric wave. A transponder chip in the key grip receives the wave. Upon receiving the wave, the transponder chip outputs a key ID code signal. The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the transponder key ECU. The transponder key ECU matches the key's ID code with the vehicle's ID code, which was previously registered in the transponder key ECU. If the ID codes match, the transponder key ECU turns OFF the security indicator. Then when the ignition key cylinder is turned, the code match results are sent through the transponder key ECU to the ECM. After the identification results show that the key's ID code matches the vehicle's ID code and the transponder key ECU has confirmed their match, the immobiliser system is canceled and the engine starting controls (fuel injection control and ignition control) enter standby mode.

 

The Immobilizer is a security component that prevents the engine from starting by disabling the fuel injectors if the incorrect key is used.

The system consists of the Transponder Key ECU (buried deep behind the instrument panel), Transponder Key Amplifier (module and coil around the ignition lock cylinder that reads the key), the transponder chip in the key itself containing the ID code, and the PCM.

When a key is inserted the Transponder Key Amplifier sends out a pulse that activates the transponder chip in the key, the key then replies with it's ID code. The Transponder Key Amplifier then transmits the key code to the Transponder Key ECU which verifies the key ID matches one of the registered key ID's, if the ID is valid it sends a signal the PCM to enable the vehicle to start. If the ID it receives is invalids or it does not receive a response from the key it will not send an ok signal to the PCM.

The remote start would either have to have some way of generating a valid key ID or a valid key transponder chip would have to be located near enough to the Transponder Key Amplifier for it to read it in order for it to start the truck remotely.