starts then shuts off after 3 seconds
02-26-2018, 09:04 AM
#2
Old fart with a wrench
Welcome to CF!
As far as I know, there are 2 reasons this could be happening. Either the security system is activated or the system is not recognizing a valid key.
The way this engine control system works is you turn on the key and the PCM becomes active and turns on the fuel pump momentarily to charge the fuel rail. When you start cranking, the crank sensor tells the PCM that the crank is turning. When the PCM gets this signal, it turns on the fuel pump and ASD relays. The ASD relay controls the ignition and fuel injector circuits. When the engine starts, the PCM looks for signals from the sensors to control mixture and rpm. These signals come from the CCD data bus which includes the Body Control Module and other functions. The BCM is the module that includes the security system. If the PCM doesn't get a "run" signal from the security system, it shuts off the fuel pump relay and the engine runs on residual pressure then dies.
If you plan on keeping this jeep, I recommend downloading the Full Service Manual from pacificcoastmanuals.com for $7.99. It's a copy of the Factory Service Manual used by dealers techs. It includes EVERYTHING on your jeep and is year specific so you don't have to paw thru useless info on other vehicles. It includes explanations, diagnosis, test procedures, and component locations for every system as well as circuit diagrams. It's 93mbs of compressed pdf files so you can print out the sections you want and throw them away when you're done if you want; greasy, dirty, ripped, or whatever.
Another good source of info is wjjeeps.com
As far as I know, there are 2 reasons this could be happening. Either the security system is activated or the system is not recognizing a valid key.
The way this engine control system works is you turn on the key and the PCM becomes active and turns on the fuel pump momentarily to charge the fuel rail. When you start cranking, the crank sensor tells the PCM that the crank is turning. When the PCM gets this signal, it turns on the fuel pump and ASD relays. The ASD relay controls the ignition and fuel injector circuits. When the engine starts, the PCM looks for signals from the sensors to control mixture and rpm. These signals come from the CCD data bus which includes the Body Control Module and other functions. The BCM is the module that includes the security system. If the PCM doesn't get a "run" signal from the security system, it shuts off the fuel pump relay and the engine runs on residual pressure then dies.
If you plan on keeping this jeep, I recommend downloading the Full Service Manual from pacificcoastmanuals.com for $7.99. It's a copy of the Factory Service Manual used by dealers techs. It includes EVERYTHING on your jeep and is year specific so you don't have to paw thru useless info on other vehicles. It includes explanations, diagnosis, test procedures, and component locations for every system as well as circuit diagrams. It's 93mbs of compressed pdf files so you can print out the sections you want and throw them away when you're done if you want; greasy, dirty, ripped, or whatever.
Another good source of info is wjjeeps.com
03-03-2018, 12:31 AM
#3
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Join Date: Feb 2012
Location: Baltimore
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Year: 2002
Model: Grand Cherokee
Engine: 4.0L (AMC) Straight Six
Yeah it's probably a problem with the SKIM (Sentry Key Identification Module) that is causing the issue... do you see a security warning light (a picture of a key with a slash through it) in the gauge cluster upon starting the Jeep? Every '99-'04 Grand Cherokee has the module. Both the key and the module have anti-theft codes stored in them. If a key that's inserted, even if cut correctly, doesn't match the code the module sends out upon startup, the Jeep won't start, or will run for 3 seconds and then shut off. If you have both original keys, you could follow the programming/reprogramming procedure and see if that fixes the problem... it doesn't require any special equipment to do.
If reprogramming your keys doesn't work, it's either a bad SKIM module or bad computer. One other thing you could do is insert the key and turn it from Off to On 3 times (don't turn the key to start), stopping on On the third time. If your Jeep has any OBD-II fault codes, they'll appear on the odometer readout and the readout will read 'd0ne' when no more codes are present. Then again, not all codes show up using that method, so your best bet would be to get the codes read for all modules. Even the cheapest of OBD-II scanners (I got mine for $15 on eBay) will do this.
Good luck on getting the issue resolved!
-Vince
If reprogramming your keys doesn't work, it's either a bad SKIM module or bad computer. One other thing you could do is insert the key and turn it from Off to On 3 times (don't turn the key to start), stopping on On the third time. If your Jeep has any OBD-II fault codes, they'll appear on the odometer readout and the readout will read 'd0ne' when no more codes are present. Then again, not all codes show up using that method, so your best bet would be to get the codes read for all modules. Even the cheapest of OBD-II scanners (I got mine for $15 on eBay) will do this.
Good luck on getting the issue resolved!
-Vince
10-06-2022, 02:16 AM
#4
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Join Date: Oct 2022
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Thank you!
Welcome to CF!
As far as I know, there are 2 reasons this could be happening. Either the security system is activated or the system is not recognizing a valid key.
The way this engine control system works is you turn on the key and the PCM becomes active and turns on the fuel pump momentarily to charge the fuel rail. When you start cranking, the crank sensor tells the PCM that the crank is turning. When the PCM gets this signal, it turns on the fuel pump and ASD relays. The ASD relay controls the ignition and fuel injector circuits. When the engine starts, the PCM looks for signals from the sensors to control mixture and rpm. These signals come from the CCD data bus which includes the Body Control Module and other functions. The BCM is the module that includes the security system. If the PCM doesn't get a "run" signal from the security system, it shuts off the fuel pump relay and the engine runs on residual pressure then dies.
If you plan on keeping this jeep, I recommend downloading the Full Service Manual from pacificcoastmanuals.com for $7.99. It's a copy of the Factory Service Manual used by dealers techs. It includes EVERYTHING on your jeep and is year specific so you don't have to paw thru useless info on other vehicles. It includes explanations, diagnosis, test procedures, and component locations for every system as well as circuit diagrams. It's 93mbs of compressed pdf files so you can print out the sections you want and throw them away when you're done if you want; greasy, dirty, ripped, or whatever.
Another good source of info is wjjeeps.com
As far as I know, there are 2 reasons this could be happening. Either the security system is activated or the system is not recognizing a valid key.
The way this engine control system works is you turn on the key and the PCM becomes active and turns on the fuel pump momentarily to charge the fuel rail. When you start cranking, the crank sensor tells the PCM that the crank is turning. When the PCM gets this signal, it turns on the fuel pump and ASD relays. The ASD relay controls the ignition and fuel injector circuits. When the engine starts, the PCM looks for signals from the sensors to control mixture and rpm. These signals come from the CCD data bus which includes the Body Control Module and other functions. The BCM is the module that includes the security system. If the PCM doesn't get a "run" signal from the security system, it shuts off the fuel pump relay and the engine runs on residual pressure then dies.
If you plan on keeping this jeep, I recommend downloading the Full Service Manual from pacificcoastmanuals.com for $7.99. It's a copy of the Factory Service Manual used by dealers techs. It includes EVERYTHING on your jeep and is year specific so you don't have to paw thru useless info on other vehicles. It includes explanations, diagnosis, test procedures, and component locations for every system as well as circuit diagrams. It's 93mbs of compressed pdf files so you can print out the sections you want and throw them away when you're done if you want; greasy, dirty, ripped, or whatever.
Another good source of info is wjjeeps.com
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