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Bad ecu?

260 Views 8 Replies 4 Participants Last post by  Keepitstock
Codes p0651 p1312. 2003 saab 9-3 arc. 1312 refers to cylinder 1&2 misfire so I swapped coils off a parts car not sure they are good. Code is still there. Read an article that said ecu sends 5v to the tps and coil packs. So before I just swapped the tps I measured at the tps connector with ignition switch on, orange wire, car not running. Was getting fluctuating reading 2.8-4.5 roughly, it was sporadic. Started car did same reading but was 3-5.5 same thing very sporadic all over the place. I tried checking coil with battery off I got nothing near 5v on any pin. Had 11.7 on the one with red wire. Any help greatly appreciated
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Discussion Starter · #3 ·
Might as well tell the story. Bought it used about a week ago. Drove well during test drive but could hear hissing thought was a turbo leak. On way home hour and half drive while accelerating from a stop would go like half boost and very little power. After it was moving would be fine. Got it home checked codes had p0300 random multiple misfire, p1312 manufacturer control, p0101 maf circuit a, p0411 second air injection, p0140 o2 sensor, also had no headlights, wipers, turn signals. Fixed headlights and signals by replacing fuse box in engine bay. Fixed maf by swapping from parts car. It’s an 04 btw most parts seem interchangeable. Fixed turbo leak plastic bracket that broke on tube which came off the rad. Battery was off when doing fuse box I guess it cleared the codes. Only codes I have gotten since then have been p1312 manufacturer control which I read is cylinder 1&2 misfire. And p0651 throttle position actuator. Other symptoms are 20mpg or less. Every once in a while has no power from stand still then once up to speed seems fine. Also only once I had warning lights for stability control and traction control at the same time. The coils on the car and ones I swapped are both saab oem but are used. Was going to swap tps but found the voltage at orange wire which I thought was supposed to be close to 5v is more like 3-5.5. That’s everything I know have at it🤪
 

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Discussion Starter · #8 ·
I appreciate the replies but honestly I can take care of replacing plugs and coils no problem. what I need to know is about the 5v that the ecu sends to what and what the tolerance is supposed to be before something is considered a problem. The 5 volts at my throttle position sensor fluctuates very rapidly. Is that normal?
 
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