GregH Posted June 30, 2009 Share Posted June 30, 2009 So I get this '08 towed in today, no crank. Verify concern, all the lights light up on the dash. P1000 in memory, KOEO passes. PID data shows STARTER_AW is "off" with the key on and in start position. EGT sensors show ambient temperature except EGRTA, which is 4.65V and 140 degrees F. The concern is present in park and neutral, but I did not verify TR data. The backup alarm sounded in reverse. The rest of the story: Vehicle died while driving on the job site yesterday. Would not crank when attempting to restart. Using the business's generic scan tool, they retrieve and clear codes - they did not record the codes, of course. The vehicle still would not crank, so it was loaded onto a trailer, sat overnight, and then brought to us this morning. Back to me in the parking lot. After the above tests, I turned the key on, went under the hood and jumped the starter solenoid wire to the battery hot terminal to crank the engine. Engine cranked and started normally. Drove the vehicle into the shop, still no codes present on continuous, KOEO, or KOER. Engine now starts properly with the ignition switch... Test drive vehicle to clear P1000, no drivabiilty concerns present... Recent repair history - replaced EGRTA for a P040D. Verified an erratic temerature reading before repair, and verified proper operation of the sensor after repair. Ultimately, I had to release the vehicle back to the owners with the understanding that they refrain from using their scan tool on it in the future.... Any idea what may have happened? Quote Link to comment Share on other sites More sharing options...
fabfoes87 Posted June 30, 2009 Share Posted June 30, 2009 Had the same concern last week with a 450. Customer had just removed aftermarket tuner and now truck would not restart. Jumped starter to power to get engine cranking. Started fine ever since. Had a code for ignition stuck in start though. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted June 30, 2009 Share Posted June 30, 2009 Years ago with Fords we had to do a "Hard Reset". This was when the PCM was making some bad decisions and needed a fresh start, similar to a Windows reboot. This was more than a reboot, though. It's when a KAM reset wasn't working and fuel trims were wacked out beyond belief. The short fix was pulling the battery cable and pushing on the brake pedal to drain the capacitors and prevent the PCM from remembering anything. (basically a KAM reset) But there were plenty of oddball vehicles that wouldn't respond to that and needed the battery cables disconnected and clamped together overnight to completely erase the PCM's memory. IIRC, this was more pre-OBD2 than later cars. I have no idea what was wrong with these trucks, but if I had to make a wild guess, I might say there was excess EMI/RFI/ACV or "chip" irregularities pissing off the PCM and it needed a fresh reboot. Even static electricity could have played a part in these trucks. Greg, If you are monitoring the EGRT_A PID while the engine is cold the value will read 140ºF until the EGR Temperature exceeds that reading. Don't let that fool you if you are diagnosing the EGR system. Your reading was normal. Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted June 30, 2009 Share Posted June 30, 2009 Down South, we called that "dumping" the PCM, not to be confused with "the PCM took a dump". Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted July 1, 2009 Share Posted July 1, 2009 Years ago with Fords we had to do a "Hard Reset". This was when the PCM was making some bad decisions and needed a fresh start, similar to a Windows reboot. This was more than a reboot, though. It's when a KAM reset wasn't working and fuel trims were wacked out beyond belief. The short fix was pulling the battery cable and pushing on the brake pedal to drain the capacitors and prevent the PCM from remembering anything. (basically a KAM reset) But there were plenty of oddball vehicles that wouldn't respond to that and needed the battery cables disconnected and clamped together overnight to completely erase the PCM's memory. IIRC, this was more pre-OBD2 than later cars. I have no idea what was wrong with these trucks, but if I had to make a wild guess, I might say there was excess EMI/RFI/ACV or "chip" irregularities pissing off the PCM and it needed a fresh reboot. Even static electricity could have played a part in these trucks. Greg, If you are monitoring the EGRT_A PID while the engine is cold the value will read 140ºF until the EGR Temperature exceeds that reading. Don't let that fool you if you are diagnosing the EGR system. Your reading was normal. Bruce... this post struck a chord... something we have referred to in respect to other readings (ICP _PRESS being one of the obvious ones - disconnect the sensor and see 750 PSI). On this train of thought.... let us explore the slightly less than obvious. An O2 sensor..... The PCM doesn't expect to see anything greater than about 1.45 volts..... Given that, the engineers program this particular device to "top out" at 1.45 volts..... You can apply V_REF to this sensor - and it will offer 1.45 volts in the data stream..... You can short the O2 heater to this sensor output (12 volts) - amazingly, your data stream will indicate 1.45 volts - simply because the programming cannot resolve anything above 1.45 volts. Thinking outside the box..... if you had a O2 concern with a ~5 volt data stream, you would think one direction. An O2 concern with a B+ reading would send you in another direction..... enabling the O2 to resolve too broad of a range of volt readings costs "computer time". On a daily basis, we have to be wary of what we look at and accept as data.... If sensor data is out of whack, we will be treated to some sort of default reading.... If we aren't prepared for this, we might be sent on a wild goose chase..... Look hard at the numbers you are seeing..... THINK..... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.