Computer module help needed

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rod7515

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Here is a pic of the module from my 98 Dodge truck. When I am trying to find another box what numbers do I have to match up? What or how do I know what these numbers mean? The person I bought this truck from was saying that it would shut off and not restart so I want to carry a spare until I figure out what the cause is. I plan on trying to find one from a salvage yard or an old truck that has been put out to pasture!
The truck is a 98 5.2L automatic, Standard cab short bed Sport.
Thanks Rodney
 

dudeman2009

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What module is that a picture of? Its location?

If its shutting down and not restarting, its probably doing it for a reason, instead of carrying a bunch of spare $300+ modules around and hoping that replacing one of them fixes the problem is just a waste of time.

What exactly is it doing? We're willing to help you, it might just take a bit of time compared to taking it to a specialty shop.
 
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rod7515

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Thats the module that is under the hood on the firewall passenger side. I havent had this truck on the road yet so I cant say when it shuts down or if it even does shut down. That is the reason the previous owner decided to park the truck and let it sit for 7 years. Im just looking for some insurance to start. I did replace the dist pickup.
Rod
 

dudeman2009

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Thats the PCM. I'd try to figure out why it shuts down first before you just throw a computer at it. Thats like looking at a house that has a small leak somewhere in the water piping, but instead of tracking the leak down, you just gut everything and replace it all.

As for the distributor. These dont have pickup coils, it's all electronic. Do you mean you replaced the cam sensor under the distributor cap?
 
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rod7515

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OK, When I went to the NAPA store they referred to it as the ignition pickup. When I just googled it it came up as an ignition pickup. So I guess it could be referenced a cam sensor as well?
Any way what I am looking for is how to decifer the numbers on the PCM module that I posted so I can try finding one in a salvage yard. What does the 343AC stand for? What other numbers would cross over? Does that PCM control the trans shift and does it have to come from a truck that was a 4wd, auto 5.2?
Thanks Rod
 

dudeman2009

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A couple things, Since you touched the cam sensor, your fuel sync is now off. It cannot be adjusted without a DRBIII scantool. It'll be about $100 to get it fixed at the dealer.

As for the PCM, i'm telling you, if its running correctly now, an intermittent stall and failure to start is rarely the fault of the PCM. A more likely cause is a failing ASD relay in the underhood fuse box. A failing crank sensor would also cause that problem. So could a fuel pump, failing ignition coil, or possibly even a failing MAP sensor.

To get a new PCM, none of the numbers on it will really help you. You'll need the VIN from the truck if you're ordering a new/remaned one from a seller. If you're looking for a junkyard PCM you'll need to match engine size, trans, 4x4 for vehicle operation, you'll also need to match A/C options, emissions as well as cruise control to prevent possible false check engine lights.
 

Merc225hp

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wow replacing the cam sensor does not mean the fuel sync needs to be reset. Ign control is done with the crank trigger (pass side behind the head on the bellhousing). These will not set a cel and might be a good cheap part to replace.
 

Merc225hp

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These are the possible pcm numbers for your truck. The number with the three *** is what's in your truck as per the pix.

05014152AA
56040557AA
56046343AA
56046343AB
***56046343AC
56046343AD
56046343AE
56046343AF
56046343AG
 

dudeman2009

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wow replacing the cam sensor does not mean the fuel sync needs to be reset. Ign control is done with the crank trigger (pass side behind the head on the bellhousing). These will not set a cel and might be a good cheap part to replace.

The Cam sensor controls fuel sync. When I was swapping engines in my truck I had to replace the distributor. The Cam sensor had a little less than a quarter inch of play once it was sat down, that's enough to throw it off. If you're lucky it won't be off my much and you can get away with it. It won't throw a code either and cannot really be checked without a DRBIII Scantool.

The distributor design might've changed slightly between years or an aftermarket part might be slightly different.

I'll change my statement to the OP to this. If the Cam sensor was tightly sat down, then don't worry about the fuel sync, if it was kind of loose, then you'll have to decide if you care about the slight error in fuel sync.
 

dapepper9

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Fuel sync is controlled via distributor rotation not cam sensor. Cam sensor is just a magnetic pickup like the crank sensor. It essentially reads cam rpm like the crank sensor reads crankshaft rpm.

Distributor, not the sensor, controls fuel sync
 

dudeman2009

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Fuel sync is controlled via distributor rotation not cam sensor. Cam sensor is just a magnetic pickup like the crank sensor. It essentially reads cam rpm like the crank sensor reads crankshaft rpm.

Distributor, not the sensor, controls fuel sync

Upon further reading, I realized the cam sensor is supposed to have a locating bit around the wire a single position on the distributor. Mine didn't have one when I replaced the distributor assembly. I guess that means i'll be replacing my cam sensor next.

As for what it does. There is a partial ring on the distributor shaft that rotates with it. When the leading edge of the ring enters the sensor's range it pusles. Its important to get the position of the distributor in relation to cyl 1 TDC. However its also important to get the orientation of the cam sensor related to the distributor housing. On my cam sensor the locating bit wasn't there, there was just the slot for the lead to exit the distributor, so it rotated a bit independently of the distributor, enough to cause fuel sync problems. I Thought that was normal.
 
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dapepper9

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Nope. Sensor/pickup goes in 1 way. Distributor housing is the only adjustment and if the distributor housings location/rotation is left untouched there's zero extra work to be done. You're overthinking it
 

dudeman2009

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Nope. Sensor/pickup goes in 1 way. Distributor housing is the only adjustment and if the distributor housings location/rotation is left untouched there's zero extra work to be done. You're overthinking it

Thats entirely possible.
 
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rod7515

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Im getting a lot of information here on this subject plus ive been reading. I dont see any information that the cam sensor is in the distributor, ive replaced cam sensors on jeeps that were in top of trans housing but i havent looked on this truck yet. I have a friend that will let me use his mac scanner to reset fuel sync if i need to. The info ive gotten to set sync was #1 tdc then place crank on v8 on balancer to tdc, find correct wire at distributer and turn dist until reading on volt meter goes from 0 to 5 volts. Start truck with scanner connected then set. What is the correct # to set at? Ive read about people setting from 0 to 4 on scanner.
Thanks Rod
 

Merc225hp

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The cam sensor is in the dizzy, this is not a heep. Using a dvm to set fs is a good way to get it up and running if you moved the dizzy, installed a new cam or t chain. Start at setting it at +4 @ 1000 rpm using a drb2 or 3.
 
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