99 Durango PCM installed but now getting new codes - any advice please?!?

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#1
I know the 99 Durango stall for no reason question has been discussed before, but I havent seen a Q&A on this one

~ truck would stall, BUS code came up and then it would start in about 30 mins.

I've installed a rebuilt PCM with a lifetime warranty. Prior to installation there were no codes (besides BUS) and the truck ran well other than the random stall-out.

Now that the PCMs been installed, the truck revs at 1,200 rpm and code 505 (idle control syst malfunction) appears.
After this, the battery was disconnected, I turned ignition key to on, waited 5 mins, reconnected the negative side of batt. and now the truck idles ALOT lower - w/o the a/c on it's idling approx 500 - just ready to stall (it did stall at a light but started right up)
Now there's no BUS.

How would I test the idle control system?

Thanks in advance for any advice!

Vanessa
 
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#2
Before we spend much time...
Tell us as much history as you can.....
accidents, maintance, etc. vehicle is STOCK no remote starter, proms, chips, aftermarket add ons? we love details as we cannot see the vehicle ourselfs

you changed the PCM- what diagnostics lead to that decission? codes? scan?

You say a code p0505 - so do you have a scanner?
 

Roy

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#3
It would help if we knew what engine, transmission, 2 or 4 wheel drive.
 
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#4
When changing the PCM on Chrysler products, don't you have to program in all those ID codes first? Do these have the learn mode?
 

billr

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#5
I am unfamiliar with the "BUS code", can someone explain so I can follow along? Vanessa, you seem to accept that stalling for "no reason" is normal. I submit that stalling is never normal, and there is a reason for it; give us some background on that issue.
 
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#6
a message appears in the information center OR the odometer "NO BUSS" - msg means there is no communication between modules
 
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#8
Here you go Bill...I know you will understand all this....Jim.............VEHICLE COMMUNICATION
The Chrysler Collision Detection multiplex system (CCD bus) consists of a twisted pair of wires. These wires run from one module to another. They receive and deliver coded information between the modules. The information is coded to identify the message as well as the importance of the message. When there are multiple messages trying to access the CCD bus at one time, the code determines the message that has the highest priority, and is then allowed to access the bus first.

The two wires of the twisted pair that make up the CCD multiplex system are called "bus +" (bus plus) and "bus -" (bus minus) respectively. Each wire has a measureable voltage level of roughly 2.5 volts . In order to maintain the 2.5 volts on each line and provide a means of transportation for the coded messages, there is a "voltage divider network" located in the module that supplies bus bias or voltage. Along with the module that supplies bias, some modules provide termination. Bias is the voltage necessary to make the bus operational. At least one point of termination is necessary, some systems may use more than one. Some modules are capable of both biasing and terminating. Termination in the circuitry (a 120 ohm resistor placed across the bus) is required to complete the voltage divider network circuit and also provide some electromagnetic protection for the bus. In this vehicle, the bias is supplied by the instrument cluster and termination is provided by the PCM and the instrument cluster. Without termination, voltage on the bus goes to approximately 5 volts on one wire and 0 volts on the other wire.

NOTE: Communication over the bus is essential to the proper operation of the vehicle's on-board diagnostic systems and the DRB III. Problems with the operation of the bus or DRB III must corrected before proceeding with diagnostic testing.

Bus Failure Messages

Short to Battery - Either or both of the bus wires are shorted to the battery potential, or open ground to any CCD bus module.

Short to 5 Volts - Either or both of the bus wires are shorted to a 5-volt potential.

Short to Ground - Either or both of the bus wires are shorted to ground.

Bus (+) L Bus (-) Shorted Together - The two bus wires are shorted together.

No Termination - The bus system has lost connection with all of its terminators.

Bus Bias Level Too Low - Either of both of the bus wire potentials are significantly below their normal 2.5 volts .

Bus Bias Level Too High - Either of both of the bus wire potentials are significantly above their normal 2.5 volts .

No Bus Bias - The bus system has lost connection with the Instrument Cluster.

Bus (+) Open - The bus (+) wire has lost connection with termination and/or bias.

Bus (-) Open - The bus (-) wire has lost connection with termination and/or bias.

Not receiving Bus Messages Correctly - The DRB cannot communicate over the bus and does not know why.
 
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#10
hi and thanks for the replies - here are the details. oh first of all, i've searched this site and have seen many with the same prob with the 99 durango suddenly stalling, showing a brief no BUS code, then starting up after about 20 or so mins.

Accident - minor (left side - changed bumper, head light, fixed fender)

its a 5. 2 liter automatic 4wd

Regular oil and tranny fluid changes, distrib caps, rotors, plug wires. Just turned 60k miles

there was an aftermarket alarm which completely removed (all wires) and brought it back to stock. Factory horn alarm still works.
there are no chips added, no aftermarket stuff.

At first i thought it was the crank sensor, changed it, which didnt help (worth a shot)
The truck stalls out approx once/wk and starts up after about 20-30 mins like nothing happened.
no code would come up except for the computer - just 3 seconds of BUS.

Searching MANY sites and asking around, about 500 ppl said its the computer and have had good luck. About 100 said it was just the ? setting motor? - i dont know if this is the throttle position sens.

I have a code reader only.

The pcm rebuilding co said it's already programmed and to just install it.

Thanks SO much for all of the replies!


btw, my Dad was a mechanic, brothers (who now live in different states) and 3 cousins are mechanics lol. Being a Daddy's girl, I was constantly working (trying) with him - we rebuilt a box nova together in the back yard. I miss him very much.

Sorry that i got off topic there :)

I hope i provided the info you need and again thanks so much for your time!
 
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#11
WOW Jim lol

Bill i dont know what the CAN is.

one thing - now that the computers been changed, it no longer stalls out for 20 mins
BUT the idle is so low that at a light, i either have to give it a little gas while waiting, or put it in neutral. If it does stall tho, it starts right up.

Code 505 is on now. So this is the idle control system malfunctioning i guess - but what part could it be? TPS, or what? if i test the ohms on the TPS, what should the range be? or can you advise me as to what else to check for.

You guys are AWESOME!!!
 
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#12
Many people may have said it is the STEPPER motor. Also called AIS or ISA with A for actuator, I for idle, and S for speed. This is the device that the PCM uses to control idle speed. It's mounted on the back of the throttle body and when it starts to fail it can cause your symptoms.
P0505 Idle System Malfunction...seems like a good match...


Bill, CCD is one of several buss communication systems that Chrysler has used in the pre-CAN years. It's not CAN. Google it.
 
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#13
You might try taking the IAC off and cleaning it with some carb cleaner...Jim............The IAC motor is mounted to the back of the throttle bodyIDLE AIR CONTROL (IAC) MOTOR-PCM OUTPUT
The IAC motor is mounted to the back of the throttle body and is controlled by the Powertrain Control Module (PCM).

The throttle body has an air control passage that provides air for the engine at idle (the throttle plate is closed). The IAC motor pintle protrudes into the air control passage and regulates air flow through it. Based on various sensor inputs, the Powertrain Control Module (PCM) adjusts engine idle speed by moving the IAC motor pintle in and out of the air control passage. The IAC motor is positioned when the ignition key is turned to the On position.

A (factory adjusted) set screw is used to mechanically limit the position of the throttle body throttle plate. Never attempt to adjust the engine idle speed using this screw. All idle speed functions are controlled by the PCM.
 
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#14
I think jim has a good idea to start the troubleshooting- clean the IAC he is not suggesting just spraying the TB.

while we have it opened for repirs thke a look at the TPS - smooth voltage swing and no issues with wiring...corossion chaffing...
 

nickb2

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#15
Hi all,
This is actually a big file for what I usually post. the chart for this code is extensive. try normal fixes such a posted by others here, cleaning IAC and throttle bore with an old toothbrush and combustion chamber cleaner. I prefer the MOPAR stuff in a bottle, not the spray.

As for the No BUS communication, that is usually not associated with a OBD2 code such as the P0505. You may have two different problems to sort out. The first one is the no BUS communication. That is a must. After, tackle the OBD2 code P0505.

this is similar to a bad ground or bad connection preventing ground back into PCM. The IAC needs ground to drive the four control drivers. See the PDF ace 1. If this ground is scrap, you may also have a non communication issue with PCM.

Check all grounds, fuses. There are a number of reasons why you have a BUS line communication problem, most likely it is a bad connection and/or 5 volt supply not getting into PCM to drive the outputs or a bad ground not allowing outputs to drive..

Ace 3 is just a picture of what you want to clean.

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