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#1
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GM3.1L no spark
As per sublect line.....no spark. Verified crank sensor working (.7v
pulses), swapped ignition module with a known good one, and have 12v at the module input. I know from past experience that a bad coil van completely knock out the spark on the rest of the coils....tried using 1 coil at a time with all 3.....no dice. Does the ECM control the generation of coil pulses at cranking or just after it gets out of open loop operation? Haven't checked for the pulse input and output at ECM yet...that's next. BTW...the voltages and grounds at ECM are OK. Need to check for the 5v reference for the sensors that use it to verify the 5v regulator in the ECM is ok. Any thoughts? Travis. |
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#2
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Try and get it on a scanner and see if the pcm is getting an rpm signal/
"boardjunkie" > wrote in message oups.com... > As per sublect line.....no spark. Verified crank sensor working (.7v > pulses), swapped ignition module with a known good one, and have 12v at > the module input. I know from past experience that a bad coil van > completely knock out the spark on the rest of the coils....tried using > 1 coil at a time with all 3.....no dice. > Does the ECM control the generation of coil pulses at cranking or just > after it gets out of open loop operation? Haven't checked for the pulse > input and output at ECM yet...that's next. BTW...the voltages and > grounds at ECM are OK. Need to check for the 5v reference for the > sensors that use it to verify the 5v regulator in the ECM is ok. > Any thoughts? > > Travis. > |
#3
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boardjunkie wrote:
> > As per sublect line.....no spark. Verified crank sensor working (.7v > pulses), swapped ignition module with a known good one, and have 12v at > the module input. I know from past experience that a bad coil van > completely knock out the spark on the rest of the coils....tried using > 1 coil at a time with all 3.....no dice. > Does the ECM control the generation of coil pulses at cranking or just > after it gets out of open loop operation? Haven't checked for the pulse > input and output at ECM yet...that's next. BTW...the voltages and > grounds at ECM are OK. Need to check for the 5v reference for the > sensors that use it to verify the 5v regulator in the ECM is ok. > Any thoughts? > > Travis. Perhaps this article will be of help: http://www.motorage.com/motorage/art...l.jsp?id=20037 |
#4
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That article was a good overview on the theory of how est operates, but
it wasn't engine specific. Now I have checked the 5v output on the ECM...its there. When checking for the ref pulse in (ref HI, ref Low) I didn't see much going on. There was some activity, but super low level. Seems to me it should be a little closer to the signal coming off the crank sensor, or even close to logic level for the ECM to use as a digital input. Speaking of the crank sensor, I read on this group someone's post describing the crank sensor "kicking the ignition module in the nuts until it collapses". I ask.....can the output pulse from the crank sensor be too high a voltage and damage the input circuit of the module? Some poster said the output of this type crank sensor should be ~300mv. Mine is putting out 700mv, whick doesn't sound like it should cause problems, but I could be wrong here. Possible for a cr. sensor to take out an ignition module? So here's where I am as of now. If the module is doing its job properly, I assume the ECM has failed. This wouldn't surprise me too much...I've already replaced it twice. Any takers? Travis > Perhaps this article will be of help: > http://www.motorage.com/motorage/art...l.jsp?id=20037 |
#5
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Some wave forms: (with volts)
http://www.picotech.com/auto/wavefor...ft_sensor.html http://www.interro.com/wav.htm#28 |
#6
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In article >,
"<< Paul >>" <" > wrote: > Some wave forms: (with volts) Good job Paul! > http://www.picotech.com/auto/wavefor...ft_sensor.html Inductive crankshaft sensor, 2 volts peak to peak on the AC scale. (there's a clue) > http://www.interro.com/wav.htm#28 Second batch down, under "Channel lab scope", the top wave form again is an inductive crank sensor, shows 8 volts peak to peak AC volts (suspect it's a running engine). 700mv isn't indicative of a good crank sensor. |
#7
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On Sat, 01 Jan 2005 07:28:20 GMT, aarcuda69062
> wrote: >In article >, > "<< Paul >>" <" > wrote: > >> Some wave forms: (with volts) > >Good job Paul! > >> http://www.picotech.com/auto/wavefor...ft_sensor.html > >Inductive crankshaft sensor, 2 volts peak to peak on the AC scale. >(there's a clue) > >> http://www.interro.com/wav.htm#28 > >Second batch down, under "Channel lab scope", the top wave form >again is an inductive crank sensor, shows 8 volts peak to peak AC >volts (suspect it's a running engine). 5 volts on a scale of 8 > >700mv isn't indicative of a good crank sensor. in a 5 volt logic circuit, 0.7 volts would be considered a logic low Lg |
#8
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In article >,
Lawrence Glickman > wrote: > >Second batch down, under "Channel lab scope", the top wave form > >again is an inductive crank sensor, shows 8 volts peak to peak AC > >volts (suspect it's a running engine). > > 5 volts on a scale of 8 Okay, 5 volts, that makes 10 volts AC peak to peak. (waveform tagged "YLO") > > > >700mv isn't indicative of a good crank sensor. > > in a 5 volt logic circuit, 0.7 volts would be considered a logic low Given the two examples posted, his crank sensor is not capable of achieving the voltage level that is characteristic of that type of crank sensor, IOWs, it's kaput. |
#9
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On Sat, 01 Jan 2005 15:21:28 GMT, aarcuda69062
> wrote: >In article >, > Lawrence Glickman > wrote: > >> >Second batch down, under "Channel lab scope", the top wave form >> >again is an inductive crank sensor, shows 8 volts peak to peak AC >> >volts (suspect it's a running engine). >> >> 5 volts on a scale of 8 > >Okay, 5 volts, that makes 10 volts AC peak to peak. >(waveform tagged "YLO") > >> > >> >700mv isn't indicative of a good crank sensor. >> >> in a 5 volt logic circuit, 0.7 volts would be considered a logic low > >Given the two examples posted, his crank sensor is not capable of >achieving the voltage level that is characteristic of that type >of crank sensor, IOWs, it's kaput. If he can buy a new one at a dealer and install it himself...that is the magic question. He needs that 5 volt output, or darn close to it. I would call anything less than 3.8 or 4 volts not good enough. Lg |
#10
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boardjunkie wrote: > As per sublect line.....no spark. Verified crank sensor working (.7v > pulses), swapped ignition module with a known good one, and have 12v at > the module input. I know from past experience that a bad coil van > completely knock out the spark on the rest of the coils....tried using > 1 coil at a time with all 3.....no dice. > Does the ECM control the generation of coil pulses at cranking or just > after it gets out of open loop operation? Haven't checked for the pulse > input and output at ECM yet...that's next. BTW...the voltages and > grounds at ECM are OK. Need to check for the 5v reference for the > sensors that use it to verify the 5v regulator in the ECM is ok. > Any thoughts? > > Travis. |
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