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Chrysler Repair/1998 chrysler cirrus no bus message

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QUESTION: HiRoland - Have a 1998 Chrysler Cirrus LXi displays "no bus" on dash when I try to start.  Thinking maybe one of my modules is not communicating with the PCM.  Need to know where Body Control Module is located?

ANSWER: The bcm is electrically and mechanically interconnected to the junction block (which is the fuse box behind the left end cap of the dash. First I would check fuses 5,8,9,11,and 15 which power the bcm. Let me know if you want the instructions for removing that combination unit.
Please read the PS below and respond to it.
Roland

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QUESTION: Thanks Roland - I checked the fuses you mentioned - checked all of them actually.  All look good. If you could send the intructions for removing that unit that would be great!

ANSWER: Hi Mike,
I wonder about your focus on just the body control module.
I am not sure that there would be any advantage to removing the unit. Rather, it would be better to try and diagnose what is the cause of the "no bus" message using a diagnostic readout box. The 'bus' is a network of several units that communicate between themselves on a pair of twisted wires. If one of those units goes bad it can shut down the bus. These include the transmission, engine, body control, airbag, anti-lock brake, and instrument cluster modules. If the engine won't start and run then I believe that the most likely way to solve this is to go to a shop/dealer that has such diagnostic readout box which will most likely be able to identify which of the participating units that constitute the 'bus' is causing the 'no bus' situation.
Let me know more about the history and details of the present condition, if there is such.
Roland

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QUESTION: You are correct - car cranks fine but won't start.  Just get "NO BUS" message.  Have tried taking to parts stores to get codes off Data Link before and they can't do because there is no power to connector.  CIL is on for something.  That is why I thought maybe BCM had issues.  Thought I would try disconnecting each unit/ module one at a time and cranking to see if message went away.  Not sure if this would work or is worthwhile?

Answer
Hi Mike,
The 12v power to the code reader connector is from the 'ignition off draw' fuse, #5 and so if that set of interior lights/door locks are working then the fuse is OK. The wire is pink in color and is on pin 16 of the data link connector. It comes directly from the back side of the junction block's 16-pin plug that is gray in color and would be found there on pin 13. Once you reestablish 12v on the plug you should be able to read codes.
Removing the participating module on the "bus", one at a time, is in fact a good approach to detecting if a module as failed that is taking out the bus.
Thanks for doing the rating/nomination which feel free to do again.
Roland

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Roland Finston

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Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

I answer questions seven days a week and respond to you in about 30 minutes. "Maxed Out" means I am answering another question, briefly unavailable, or asleep overnight, so try again later.

I have do-it-yourself experience (50+ years) and a library of 100 1982-2012 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

I was voted "Top Expert" 2010-2015, here at AllExperts, and have answered 20,000+ questions.

Experience

Five decades as a 'do-it-yourselfer' on domestic and imported cars.

Organizations
Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Education/Credentials
Advanced degrees in Physics/bruised knuckles

Awards and Honors
"Top expert" of 2010, 2011, 2012, 2013, 2014 and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

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