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Discussion Starter · #1 ·
Good Evening Everyone,

So...

I've got a 1997 Ram 1500 4x4 with the 5.9l V8. When I start it, it stalls out immediately. No chugging or anything else, the RPMs just drop off and it doesn't recover. It runs fine, but I've got to work the brake and throttle pedals at the same time. I have replaced the IAC previously. Before, it would be a year or so between failures. This last time was about 2 months before it started doing it again today. After seeing the pattern, my question is:

What is the background issue? What are the other potential causes for the premature failure of the IAC? And the other potential issues that could be related?

I turned the key 3 times and got these codes, in order, as presented:

12: Battery Disconnect
Direct Battery input to PCM disconnected within last 50 ignition key-on cycles. Normal if battery has been disconnected, otherwise check battery power and ground connections.

25: Idle air control motor circuits
A short is detected in one or more of the idle air motor circuits.

21: O2S Stays at center
O2S shorted to voltage
O2 sensor does not detect rich or lean condition, or O2 sensor input voltage too high. DRB will indicate which side with dual sensors. The O2 sensor signal should fluctuate under normal conditions.

25: Idle air control motor circuits
A short is detected in one or more of the idle air motor circuits.

55: N/A
End of message code. A DTC 55 is used to end all DTC messages. This code does not show on the DRB tool and indicates a completion of the stored codes on the Malfunction Indicator Lamp (check engine lamp).

That spawns another question: Why did I get 25 twice? Are there multiple IACs present?

Any help would be greatly appreciated.

V/R,

Jason



Also, I looked at the air filter, and there seems to be oil blowing on it. I've read in other posts about the plenum gasket leaking and causing idle/stall problems. Could this be the case?
 

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Oil on the filter is usually a bad pcv valve, cheap from the dealer. The only way to check for a plenum leak without removal is to take the airhorn off the throttle body and using about a 1 1/2' homemade qtip , push it thru the open throttle body mouth to the passenger rear corner of the throttle body. If it comes back oilly then you have a leak. Clean you are okay. Any leak and oil will pool at that corner.
 

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Sounds like you have wiring issues too with the shorts showing up...
 

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Go thru all the ground connections you can find, disconnect and clean with small steel brush then reconnect. Bad grounds/dirty/rusty will cause all kinds of problems........BTW, any time the "computer" detects a fault, that fault is stored as a hard code, so same problem can have multiple hard code stored. A scan tool or disconnecting the battery for a few minutes should reset the codes.......Good luck!
 

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Discussion Starter · #5 ·
Killer, thanks guys. I do have another question on checking shorts...

How do I do it with a voltage meter?

I can do a visual inspection, but if that doesn't yield anything, I will need to know how to test it for short.

Once again, thanks!
 
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