Chrysler Repair/intermittent shutdown problem: 3.3L '99 minvan
In continuation to the above question thread:
Replacing speed sensor did not help. It is still doing the same intermittent shut off thing. Though over the time, I have noticed the following:
1) Whenever it happens, it happen several (3-10) times in succession and then it will not happen for some time that varies but there is clearly a time period (not the same always) when it does not happen and will repeat in the same manner.
2) Although it has happened on the highway, when my foot was firmly on the gas, it usually happens when my foot is off the gas and if I am able to press the gas quickly as the engine is cutting off (the rpm needle starts going towards zero), it usually restarts most of the time.
Do these point towards anything specific?
Thanks for your help.
ANSWER: Absent any fault codes (did you try recently?) it may be a flaky ignition switch or some wiring related to the section of the switch which powers the pcm. Try jiggling the key when it happens, and even when it doesn't happen try to see if you can induce the behavior.
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QUESTION: With your help in the past several months, I have almost checked all possibilities. Specifically,
1) I have checked the ignition by jiggling the keys and jiggling the wires under the steering column cover.
2) Cleaned contacts for ECM, fuse box etc.
3) Checked MAP and throttle sensor voltages
4) Cleaned throttle body, EGR valve and idle control valve
5) Changed speed sensor on transmission
6) Checked/taped all under hood wires
I cannot duplicate the problem! No codes! As a matter of fact, I bought a code reader that can provide live data from engine but the code reader is also disconnected whenever this happens (I believe this means that ECM/PCM is actually turning off!)
ANSWER: If you mean by "the code reader is also disconnected" that it goes completely dark (no power) then that means either a momentary loss of power from fuse 28 (the ignition off draw fuse which powers it, or the positive connection of the entire vehicle to the + post clamp of the battery) or the disconnection of one of its 2 ground wires connected to the negative battery post clamp or the ground wire under the dash at center support of the dash where there is a many-wire ground point. If you mean it stays illuminated but looses it data then that would be an issue with the digital data bus twisted-pair bus wires.
So check all the ground wires and the - post clamp wires where they are grounded at their far ends, and check the + post clamp wires. Somewhere you have a rotted connection that takes out both the data link connector and the engine function.
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QUESTION: The code reader, kind of hangs on the live data. It does not go dark but restarts by itself and reconnects to the OBD system in van and ends up at the home screen menu.
If it goes dark for a fraction of second then I cannot notice that since the van is back to normal in no time after the shut down episode.
I forgot to mention that I have changed the battery initially thinking it might be internally related to the battery. I have cleaned the posts, clamps, ground points below the battery tray, at the engine and behind the radio with no gain. The negative clamp was rotted and I changed it; I noticed some of the green powder (that dissolves in the baking soda solution) that forms on the clamps/posts in between the strands of wires on the thinner negative cable. I also re-soldered the weak points on the instrument cluster.
Where is this fuse 28 located? How to check the twisted-pair bus wires for the digital bus?
If you would have a passenger on-board watch the code reader that might indicate if the problem is in the data bus wire systems, or the power supply. The thinnest ground wire on the - post clamp would be a good suspect as well as it one of the two grounds for the reader and many of the electronic devices. The data bus wires are no different from others, just twisted and the network is large so it will be a search to find a problem with them. You may have to wait for it to get worse so you can trouble-shoot in a fully shut down condition.