QuestionQUESTION: HI Roland i have a 1994 lhs and i'm having problems with it starting it acts like it wants to start but wont, my husband got a code. but now he can not get it to read a code, he had the cam sensors tested,spark coil pack,map sensor,along with mulitable other things and they all tested good, could it be the computer? or is there something else he could check?
Thank You
ANSWER: Hi Chris,
Does he only get a 55 code, or no flashing at all of the check engine light? If no flashing at all, then it could be a problem with the ignition switch having a section with poor connections in the part that powers up the computer. So tell me about that.
Do you hear the fuel pump run for a second when you turn the key to the 'run' position, as is normal. Has he tested for spark at one of the spark plug wires while you crank the engine over? Those are the tests to do first. I can tell him about the wires to check for the ignition switch question if he has a voltmeter or glow light.
Roland
Thanks Roland, He has done the spark test and he hears the pump come on and changed the pcm, he does have a standard 12v glow light, he does not get any flashing at all at the check engine light? could you help him with the wires? Thank You, Christine
Hi Chritine,
When you say "done the spark test", was there spark?
In any case, if the fuel pump runs for a second, that would be a fairly good indication that the power is getting to the pcm. Just in case he could verify that he has power on fuse 18 behind the dash when the ignition is on 'run'. And check fuse B in the underhood box which should show 12v all the time. Those are the two power supplies for the pcm.
I wonder whether he still has the original pcm or not. Is it possible that the one he got is from a 96-later donor car, as those may not have the code readout via the ignition key approach but rather require a code reader. Does the check engine light still come on? but doesn't flash, or does it not come on at all (in which case it might be a sign of a communications bus failure in the system that involves several modules) and/or a problem with the connection of the plug/socket to the dash circuit board? I don't believe it is a problem with the ignition switch since the fuel pump runs for a moment (which is mediated by the pcm).
Thanks for the nomination. You will probably have to respond by a 'follow-up' new question. But whatever answers to the above you could share would be helpful.
Roland
---------- FOLLOW-UP ----------
QUESTION: Thanks Roland,
He has done the spark test and he hears the pump come on and changed the pcm, he does have a standard 12v glow light, he does not get any flashing at all at the check engine light? could you help him with the wires?
Thank You,
Christine
AnswerWhen you say "done the spark test", was there spark?
In any case, if the fuel pump runs for a second, that would be a fairly good indication that the power is getting to the pcm. Just in case he could verify that he has power on fuse 18 behind the dash when the ignition is on 'run'. And check fuse B in the underhood box which should show 12v all the time. Those are the two power supplies for the pcm.
I wonder whether he still has the original pcm or not. Is it possible that the one he got is from a 96-later donor car, as those may not have the code readout via the ignition key approach but rather require a code reader. Does the check engine light still come on? but doesn't flash, or does it not come on at all (in which case it might be a sign of a communications bus failure in the system that involves several modules) and/or a problem with the connection of the plug/socket to the dash circuit board? I don't believe it is a problem with the ignition switch since the fuel pump runs for a moment (which is mediated by the pcm).
But whatever answers to the above you could share would be helpful.
Thanks for the nomination. I sent this same answer a minute age as a revision of the earlier answer. So don't be confused. You can use the thank/rate tab again as this is a 'new' question.
Roland
yes there was spark, and yes he does still have the old pcm, can you check the main plug to the coil wires with a glow light tester?
Hi Christine,
If he has spark why test the coil, it works? I have another idea that doesn't involve spark but rather mixture, and also won't be easily detected by the engine controller and thus set a code: the egr, one of my favorites when bad idle/no start rears its ugly head. I would take a look at the exhaust gas recirculation valve which is located behind the engine near the air intake throttle valve. It is mounted in a pipe that runs between passenger side exhaust manifold and the air intake manifold. The valve is mounted horizontally and has a valve stem between its round vacuum actuator top and the body of the valve attached to the pipe, inside the flange that connects the two parts. The stem has a slot into which you can insert the tip of a flat-bladed screwdriver so as to lever the stem back and forth against spring action which should move freely and close tightly. If the stem seems to be sticky so that stem doesn't close all the way by spring action, then you can try spraying some penetrating solvent like WD-40 on the valve stem to freeup its motion.
If the valve is sticking slightly ajar (particularly when cold) it will make for a no start such as you describe because the mixture is too dilute. It is one of the most common causes of this symptom. So see if you can find the valve and check/lubricate the stem. It may be that the interior of the valve is cruddy so that might require that it be unbolted from the pipe where it it attached and cleaned. But chances are good it will only be a sticky stem. Feel free to write back with the results and other questions you might have.
Roland
PS Thanks for the nomination.
