1999 1500 5.2 possible PCM issues? no bus, Lost
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12-26-2018, 11:27 AM
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1999 1500 5.2 possible PCM issues? no bus, Lost
I have a 1999 Dodge Ram 1500 with a 5.2L engine in it and about 204,000 miles approximately. Lately I have been having some issues I am a bit lost on. I have had the truck for the last 70,000 miles with no issues other than minor things such as replacing the radiator, water pump, etc. The transmission was rebuilt around 180,000 and no issues with the truck until now.
About 8 months ago my check engine light turned on and stayed solid. Even though the truck was running fine and no shop could retrieve a code from the PCM the check engine light would not go off. Due to some budget issues I was not able to take the truck in for 4-5 months. I drove it from time to time but it sat more than it was driven. It probably drove around 2500 miles with CEL on with no apparent issues and during that time and never once able to retrieve a code.
Finally I bit the bullet and took it to a man who worked for a local Dodge dealership for 15+ years and opened his own shop. He was able to finally pull a code P0443 "EVAP system Purge Control Valve "A" Circuit" however he checked the circuit and told me that the circuit was fine. He said that the PCM was no good and that it was throwing that code as a "phantom code". He quoted me $1100 to fix it which is not an option for me, so knowing that I could get a PCM online for around $300, I went ahead and ordered one up. The company has great reviews, claims to specialize in Dodge PCMs, and said to just provide mileage, transmission, and VIN and it would come plug and play, no relearning process necessary.
My newly purchased PCM came in the mail so, I disconnected the battery, unscrewed the PCM and installed the new one. One of the screws had a ground cable which I made sure to reinstall as well. The CEL illuminated shortly after starting the truck, however this time I was getting codes P0207 & P0208 Cylinder 7 & 8 Injector "A" Circuit. Keep in mind my truck was having no driving issues or anything I could tell prior to this. I decided to drive the truck in my neighborhood to see what I was dealing with and my truck had no power whatsoever. From a stop i could barely get above 30 MPH flooring it. The truck began to misfire on cylinder 7 & 8, random/multiple misfire as well on top of the circuit codes also still showing. Having known that my truck displayed zero of these issues with the old PCM I reinstalled it and called the company back. My truck ran fine, had power and no misfires with the old PCM reinstalled. The PCM company sent me out a new one...
Second PCM came in. I installed it in the same manner as the others and viola CEL gone, no issues with driving or anything. For ten days my truck did fine. One night I am coming out of a parking lot and I accelerate to cross over some lanes and as I am slowing down after crossing into the furthest lane and coming to a red light my truck suddenly loses power the CEL flashes but goes right back off immediately. The truck did not shut off, it just seemed like it skipped a heartbeat. I checked for codes and the computer had nothing.
A few days later, maybe five days, I am driving back from the grocery store and come to a stoplight. I suddenly feel like my truck has turned off. No sputtering no acting weird it simply just shut off. I tried to restart it and it would not restart. I push it across the street and let it sit for a 10-15 min period while i tried to figure out what to do. After that waiting period it decided to start again, so my first thought was "GET HOME" however the next stop that I came to it shut off again. So, I push it to the side of the road and let it sit for 10-15 again. This time I start it and just let it run. After about 5 minutes of running it shuts off on its own and throws me the "no bus" on trip meter. I decided to call a tow truck because there was no way i could make it home with it turning off at every stop.
Fast forward a few days after that incident, and I go outside to start my truck and let it run. It runs for 20-30 minutes without turning off at all. I did not drive it because I was too scared of it getting stranded, but just sitting there in front of my house it ran like it had no issues.
At this point I have no idea where to start. Is it the new PCM? the old one never had these issues despite being defective and not being able to store codes. Is it something on part of the 5v circuit? Is it something else? I am having trouble believing it is the PCM if it starts and runs for 30 minutes without and issue and my scanner is able to communicate with it. The only time my scanner cannot is when it shuts off on its own and goes into "no bus". If the computer was bad would it not "no bus" all of the time? This is a brand new computer. Before I call them back up I just want to make sure I do not truly have an issue on my side.
Some other things to note:
The same man that initially told me my PCM was bad also said my alternator was making a bit of noise and to think about replacing it, however it is still charging my battery to full, so I am not sure if that is a factor.
Second, my ABS and BRAKE light have both been on for some time, I replaced the sensor on the rear differential already with no success.
Third, I have some pretty gnarly mud tired that send a lot of vibration through the truck.
Any tips on where to start would truly be appreciated. I am a bit lost here. I am not a mechanic but have done many repairs on my truck with the help of good folks like yourselves.
About 8 months ago my check engine light turned on and stayed solid. Even though the truck was running fine and no shop could retrieve a code from the PCM the check engine light would not go off. Due to some budget issues I was not able to take the truck in for 4-5 months. I drove it from time to time but it sat more than it was driven. It probably drove around 2500 miles with CEL on with no apparent issues and during that time and never once able to retrieve a code.
Finally I bit the bullet and took it to a man who worked for a local Dodge dealership for 15+ years and opened his own shop. He was able to finally pull a code P0443 "EVAP system Purge Control Valve "A" Circuit" however he checked the circuit and told me that the circuit was fine. He said that the PCM was no good and that it was throwing that code as a "phantom code". He quoted me $1100 to fix it which is not an option for me, so knowing that I could get a PCM online for around $300, I went ahead and ordered one up. The company has great reviews, claims to specialize in Dodge PCMs, and said to just provide mileage, transmission, and VIN and it would come plug and play, no relearning process necessary.
My newly purchased PCM came in the mail so, I disconnected the battery, unscrewed the PCM and installed the new one. One of the screws had a ground cable which I made sure to reinstall as well. The CEL illuminated shortly after starting the truck, however this time I was getting codes P0207 & P0208 Cylinder 7 & 8 Injector "A" Circuit. Keep in mind my truck was having no driving issues or anything I could tell prior to this. I decided to drive the truck in my neighborhood to see what I was dealing with and my truck had no power whatsoever. From a stop i could barely get above 30 MPH flooring it. The truck began to misfire on cylinder 7 & 8, random/multiple misfire as well on top of the circuit codes also still showing. Having known that my truck displayed zero of these issues with the old PCM I reinstalled it and called the company back. My truck ran fine, had power and no misfires with the old PCM reinstalled. The PCM company sent me out a new one...
Second PCM came in. I installed it in the same manner as the others and viola CEL gone, no issues with driving or anything. For ten days my truck did fine. One night I am coming out of a parking lot and I accelerate to cross over some lanes and as I am slowing down after crossing into the furthest lane and coming to a red light my truck suddenly loses power the CEL flashes but goes right back off immediately. The truck did not shut off, it just seemed like it skipped a heartbeat. I checked for codes and the computer had nothing.
A few days later, maybe five days, I am driving back from the grocery store and come to a stoplight. I suddenly feel like my truck has turned off. No sputtering no acting weird it simply just shut off. I tried to restart it and it would not restart. I push it across the street and let it sit for a 10-15 min period while i tried to figure out what to do. After that waiting period it decided to start again, so my first thought was "GET HOME" however the next stop that I came to it shut off again. So, I push it to the side of the road and let it sit for 10-15 again. This time I start it and just let it run. After about 5 minutes of running it shuts off on its own and throws me the "no bus" on trip meter. I decided to call a tow truck because there was no way i could make it home with it turning off at every stop.
Fast forward a few days after that incident, and I go outside to start my truck and let it run. It runs for 20-30 minutes without turning off at all. I did not drive it because I was too scared of it getting stranded, but just sitting there in front of my house it ran like it had no issues.
At this point I have no idea where to start. Is it the new PCM? the old one never had these issues despite being defective and not being able to store codes. Is it something on part of the 5v circuit? Is it something else? I am having trouble believing it is the PCM if it starts and runs for 30 minutes without and issue and my scanner is able to communicate with it. The only time my scanner cannot is when it shuts off on its own and goes into "no bus". If the computer was bad would it not "no bus" all of the time? This is a brand new computer. Before I call them back up I just want to make sure I do not truly have an issue on my side.
Some other things to note:
The same man that initially told me my PCM was bad also said my alternator was making a bit of noise and to think about replacing it, however it is still charging my battery to full, so I am not sure if that is a factor.
Second, my ABS and BRAKE light have both been on for some time, I replaced the sensor on the rear differential already with no success.
Third, I have some pretty gnarly mud tired that send a lot of vibration through the truck.
Any tips on where to start would truly be appreciated. I am a bit lost here. I am not a mechanic but have done many repairs on my truck with the help of good folks like yourselves.
#2
12-27-2018, 01:55 AM
I would put my money on an intermittent electrical issue, and double or nothing on all PCMs being good. If you're in the rust belt check all wiring meticulously. Power supply and ground obviously, but if the 5V sensor supply gets shorted to ground it also causes all sorts of havoc. Similar with the CCD bus. You might also try to disconnect the "Controller Antilock Brake (CAB)" in case it affects the bus as it already seem to have issues.