2004 Quest - no-start troubleshooting, appears ignition related. No codes (battery was unfortunately removed)
Checked fuses, pulled plug and checked for ignition (none apparent). Engine has fuel (pump operation verified), camshaft and crankshaft position sensors replaced. Occasional fire, but won't run (same as before sensor replacement). Minutes prior to failure, the engine was running VERY rough at idle and ok at cruise, then quit instantly at cruise. No fall-off.
Hi, did the engine light when on before it stall, are there any codes present?
Engine light was on for some time prior to the failure. No codes as indicated in my description.
ok,if the engine light when on there should be some pending codes stored on the computer even if the light is not on ,did you scan the pcm and tcm to verify no codes?
have you check for spark?, does the engine light turns on with the key turn to on(not running)
I was unable to read the codes before I yanked the battery out (bad reader). I never saw them prior to the battery removal. I checked for spark and had none. The engine light is ON when the ignition is ON. No new codes have been entered.
ok have you check your primary circuit (ignition coils) for 12.5 volts suply
No. Are the always hot and switched ground?
you mean the coils get hot?
no. I meant to ask if the coils are always powered, with the ECM switching the ground on/off to energize them.
I'm going to go check them here shortly and will let you know what I find.
here is the wiring and fuse together with the relay location in case there is no power to the coil check the fuse located on the fuse box at the engine compartment and if ok then locate the relay and try another relay from the same box then let me know any results .
While fiddling around this afternoon, I found a reference for manually checking codes without a reader and came up with P1031 and P1051. The writeups on these were confusing as some seemed to indicate O2 sensors while others said it needed an ECM reprogram. could either of these be related to the current issue we are working?
Thanks for the diagram. I'm off to check that now.
let me look up this codes and get back to you.
this codes are for the air flow sensor and 02 sensors , check fuse#46 at the engine compartment fuse box also and let me know if ok.
I checked the coils and they have 12v with the ign ON. I'll have to go back and look at fuse 46
I can't identify fuse 46 by number. Is there a fuse location legend (not the one on the box cover) or do you happen to know the label associated with that particular fuse?
I'm a little confused on the fuse number as the illustration only shows fuses up to #32
Thanks by the way for helping decipher where and what in the EC manual to investigate.
Sorry. Just realized that the iIlustration  is for pin numbers, not fuse numbers.
ok so you have power to the coil, lest check if you have switching ground to the coil on the other wire do you have a test light?
I do have a test lamp. Not LED, so I'm wondering how successful it might be. The coils appear to be 3-wire. I'll check that tomorrow.
The coils are 3-wire. Red (power), black (presumed ground) and white (switched ground?). With the ignition OFF, both the black and white wires are grounded. Does this condition change when the engine is started? I'm trying the test and will let you know the results.
test results. When cranking the engine, I get maybe 1 weak spark from a coil which is consistent with the engine occasionally attempting to start. After that spark, nothing. I tried the trouble light test but can't confirm there is any cycling of the ground circuit on/off.
I see in the schematic that their is a condensor in the coil circuit. In an old points system, that would be to prevent point arcing. What function does it serve here?
Hi, the condenser is there to filter electrical interference to the computer cause by the magnetic pick up and the coil, the white wire is the ground trigger wire from the computer if you place a test light between the white and the red you should see a bright light on the test light as you crank the engine.
you say after the coil fires one time then there is no more spark how about the test light does it continues to flicker?