QuestionQUESTION: Engine cranks will not start,have occational week spark on #1. I have replaced the coil same problem.There is a constant test light while cranking on the coil input wires(no flashing).I would appreciate any input you would have Thanks.
ANSWER: Hi Dennis,
The '96 should be able to tell you any fault codes stores in its memory by means of the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which remains "on", to begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat to asure an accurate count. Then combine the numbers in pairs in the
order of appearance to form the two digit fault codes. Code list is available at www.allpar.com/fix/codes.html or write back and tell me the results. As regards the flashing light, are you turning the engine by hand with a socket on the crank pulley bolt, or are you turning it over via the starter motor? If the former then that would be a useful observation; if by the starter motor then the test light may not be accurate. But let's see what the fault codes say.
Roland
PS Use the 'thank/rate' tab to get back to me with the results, and without having to wait for me to be 'available' to take a question. There is a space there for comments to which I will reply.
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QUESTION: Hi Roland, Codes 12,55. Was cranking engine over with starter motor, also very rarely while cranking it will back fire through r/h intake(has new plugs &wires)
ANSWER: Hi Dennis,
I assume that you hear the fuel pump run for a second or so when you turn the ignition switch to run, which is normal. If you are getting no spark, then you need to verify that you are getting 12V on the dark green/orange wire at the coil for the same 1 second or so. Then when you crank it are you getting a re-appearance and continuing 12v on that wire as long as you crank? I believe you would do better with a volt-ohm meter rather than a test light.
If you are, then check whether you are getting 12V that pulses to 0v, on the other three wires at the coil plug, once per revolution on each of the wires.
The combination of a steady 12v on the dark green/orange and pulsing on the other three coil "driver" wires should, when applied to the coil produce secondary sparks reliably. If not, tell me what you observe.
If you aren't getting the driver pulses then check whether the cam and crank sensors are pulsing between 5V and 0.3V numerous times per revolution when the engine is turned over by hand with a ratchet on the crank pulley bolt. You would measure between the common ground for both sensors (black/light blue) and signal wire which is tan/yellow for the cam sensor, and light blue/dark blue for the crank sensor. The orange wires at each sensor should have 8V on it steady as well or there can't be any pulses. Of course all these are measured with the ignition in the run position.
You will thus be checking the primary circuit for the spark system which as you described it seems to be very weak.
The cam and crank sensors are what tell the controller to pulse the driver wires.
Let me know what you find.
Roland
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QUESTION: Roland, did as you recomended,cranked engine over by hand and had o-12v pulses on each of the three coil input wires but also had pulsing on the constant 12v green wire. By chance I checked for codes again after checking for pulses and Got 12,42,42,55 w/key on off method but no codes with my scan tool. The 42 codes tell me thereis an ASD problem and using the check out procedure from alldata it tells me to replace the PCM, If so I guess I go junkyarding to find one.Does it make sense to you. Thanks Dennis
AnswerHi Dennis,
Before doing that, try jumping the front pin to the back pin socket of the ASD relay socket with the relay removed (temporarily only of course, otherwise the fuel pump and coil runs all the time) and see if it will start. If it does, try substituting another relay in the box for the ASD (with the same part number) and see if it will run.
If not, check that you have a solid 12V on the front pin while cranking (which should be there all the time from fuse B in the box), and check the dark green/orange wire (most accessible at the alternator) to test if there is something flakely in that ASD output wire, and check fuse #18 behind the dash while cranking for a solid 12V, and finally check the continuity from the in-board pin of the ASD to pin 51 of the powertrain control module while shaking the harness to assure that wire isn't flakey. Those are the 4 wires of the ASD circuit which you would want to verify before going for a new pcm.
Roland
Roland, Checked ASD system OK, Did you mean Pin #67 not #51 for continuity from inboard ASD terminal if so it all checked out ok seems to be pcm thks Dennis
Hi Dennis,
Yes, thanks for that correction. I inadvertantly was looking at my '94 wiring diagrams and assuming they applied to your '96! I should have used the '98 (my only other option). Between the 4 years, the controller changed from a single 60-pin plug to 2x40-pin plugs with different pin assignments. I wonder which was the case for the '95? I'll assume it's like the '94 until proven otherwise.
I suppose as well that you have the long-thin power distribution box under the hood, rather than the nearly square one shown in the '94 manual. Otherwise, please let me know.
I hope some of this checking has improved things for you. Did the engine run with the ASD relay by-passed? You might want to disconnect the battery to erase all the old codes (except the consequential 12 code) and see what comes up now. It could be that one of the rotational engine position sensors is putting out a weak signal that is not so bad as to set a code but still causes a no start/poor spark and the 42 code.
