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90 Seville Strange Behavior


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I have a 90 Seville. I am experiencing strange readouts from my ECM and BCM. They are mostly intermittent. The car drives pretty much as normal, though with some roughness at idle and a bit of extra cranking at start up. ECM error code EO12 is pretty much constant. BCM error code B127 is also pretty much constant. The "service engine soon" telltale is on constantly. It lit up for the first time about 6-8 months ago but since the car was running fine, I ignored it. The ECM data indicates an engine temperature of 303 degrees F, (150 C) from start up. The speedometer reads 0 mph most of the time. The engine data reads 0 rpm most of the time. The "gear select problem" message comes on at start up and the PRND123 indicator is boxed. After driving around studying the ECM data for about half an hour, I was stopped and the car sort of lurched or shuddered slightly, then most everything went back to normal. When I got home and shut it down, I restarted and the problem readouts had all returned. What would cause all these unrelated symptoms?

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I have a 90 Seville. I am experiencing strange readouts from my ECM and BCM. They are mostly intermittent. The car drives pretty much as normal, though with some roughness at idle and a bit of extra cranking at start up. ECM error code EO12 is pretty much constant. BCM error code B127 is also pretty much constant. The "service engine soon" telltale is on constantly. It lit up for the first time about 6-8 months ago but since the car was running fine, I ignored it. The ECM data indicates an engine temperature of 303 degrees F, (150 C) from start up. The speedometer reads 0 mph most of the time. The engine data reads 0 rpm most of the time. The "gear select problem" message comes on at start up and the PRND123 indicator is boxed. After driving around studying the ECM data for about half an hour, I was stopped and the car sort of lurched or shuddered slightly, then most everything went back to normal. When I got home and shut it down, I restarted and the problem readouts had all returned. What would cause all these unrelated symptoms?

E012 is no distributor signal

B127 is an error with PRNDL signal

If the computer thinks it's 303 degrees all the time, then the temp sensor is off, too. I'm surprised one will run at all with E012 code, which also explains the tach readout of 0. Between that and your speedo reading 0, I'd assume that your cruise doesn't work. The computer is having to fly blind on running the engine with some of it's signals missing. I would not be surprised by shudders and poor idle, and I'd expect an SES light for these problems.

If all of these problems came up at the same time, I would suspect a wiring or ground problem.

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