Mechanics

HORN ALWAYS BLOWS, CLASS 2 MALFUNCTION, CAR OVERHEATS, AND CIG. OUTLETS DONOT WORK

1997 Cadillac El Dorado • 127,548 miles

(horn)blows when pluged in.

(car overheats) fans only come on when a/c is on but they run low.

(cig outlets and phone) no power to both.

ran onboard diag. Codes and got ipc u1255 current--class 2 communication malf. Serial data line---? How do you fix this
also got code msm b2120 history ---lumbar up down sensor fail---

would any of these cause a short to ground

any help would be great thank you
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Keithcover
March 23, 2012.




DTC U1255, CLASS 2 INITIALIZATION ERROR

When vehicle is started, PZM requests information from other modules on Class 2 serial data line. DTC U1255 will set when PZM request information from a particular module, and that module is not "on-line". PZM will then use default values. DTC U1255 will clear when module providing the requested informations comes back "on-line".

Testing

1. Clear DTCs and cycle ignition. Check for DTCs. If DTC U1255 exists, use scan tool to establish communications with each module on Class 2 data bus. Repair or replace as necessary.

2. Check for intermittent open in Purple wire between individual control modules. If circuit is okay, replace PZM.

B2120 is for the seat and is not likely be the cause of the problem. Get U1255 resolved and see if other problems are cured as well.

KHLow2008
Mar 23, 2012.


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