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No bus ground issues 2001 1500

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Old 01-27-2024, 06:20 AM
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Default No bus ground issues 2001 1500

So I apologize if there’s already a post about this but I’m having current issues so I wanted to know if anybody had any ideas

I have a 2001 Ram 1500 5.9 V8

out of the blue while it was idling it just stopped Dead. Followed by a no bus statement on the odometer Spontaneously I can get it to start but usually within three minutes it will automatically just shut off by itself with the key in the on position
I assume it might’ve been a crank sensor, so i changed that out it appeared to run better, but still had that three minute Window before shutting off automatically
Other than the gauge cluster not activating correctly causing a no start and now a left front headlight is not turning on. I’m assuming it’s probably a Ground issue anyone have any idea I would appreciate it



 
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Old 01-27-2024, 09:27 AM
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Have a look at G100. Drivers side, in front of the battery, WAY down on the inner fender. It's a stud that sticks straight up, and there are more than a dozen wires going there.... all to a single connector.
 
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Old 01-27-2024, 09:28 AM
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yea that is a location I was assuming might be the problem thanks hopefully it’s the answer

thanks
 
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Old 01-27-2024, 10:46 AM
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So I made sure all those grounds were good in that left fender spot. I was able to run it for about five minutes and was able to move forward and backwards and a short distance I went back to Park and within probably a total of three minutes it just died And went back to no bus
 
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Old 01-27-2024, 11:47 AM
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Have a scanner that can read live data? See what is happening at the three minute mark. Probably one of your sensors is failing..... all it takes is just one on the 5 volt bus, and yer done. WHICH one though, becomes the question.
 
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Old 01-27-2024, 12:05 PM
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So far, I haven’t been able to get it to restart
When it’s in this no bus mode, it shows up with no communication on the port
I did the self diagnostic on the cluster and it came up with a 921,922 and a 999 cluster code

I also spent time and tried to clean the main connectors on the front distribution box, and under the dash
 
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Old 01-27-2024, 12:27 PM
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Cluster test doesn't really help. You will get most of those errors even when everything is working properly.

Try unplugging sensors one at a time, and test if you still get the no bus error.
 
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Old 01-27-2024, 01:03 PM
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So at the moment I’m getting a continuous no bus the only way I can unplug sensors and get a no bus as if it’s actually going to react like that
I went around with the probe and checked my grounds under the hood. They all appear to be good, including the one for the PCM. Other than an ECM ground that I was told supposedly is near the starter.
I don’t know where there is other ground locations under the dash
 
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Old 01-27-2024, 05:35 PM
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So I have an update, I thought that it was my throttle position sensor because I was getting no signal while the pigtail was plugged into it, but I could get it when it was unplugged. I changed it and it ran good for about 30 minutes. I was able to drive it around the block once and then it just died and went back to the no bus issue. Kind of running low on options. I didn’t see any issues with the live data. And I kind of feel that it might be unlikely that it’s the module itself because it does have these moments of operating properly unless it’s just a short in the harness somewhere or something?
 
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Old 01-27-2024, 07:54 PM
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"no bus" means the cluster doesn't get any data from the PCM. While it could be that something faulty is causing havoc on the bus, the fact that the scan tool can't talk to the PCM in the "no bus" state would indicate the PCM itself is down (Basic OBD2 does not use the CCD bus). Double check the basics, power & ground. On PCM connector 1 pin 2 is switched power (light green/black), pin 22 is permanent power (red/white), pins 31 and 32 are ground (black/tan). The grounds go to G105 at the front of the engine. You can check the ground via the OBD2 port pin 5 (black/tan) which goes to the PCM and from there to G105.

Edit: Also make sure that the engine ground strap is good.
 

Last edited by DerTruck; 01-27-2024 at 07:57 PM.


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