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General Forums => The Mess Hall => Topic started by: bumati on November 28, 2010, 08:49:12 AM
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Went out and started Jeep. Let it idle a few. Died. Ok checked fuel line that's good. Next was
the ignition system. Replaced coil cap rotor and plugs (yes I have spares). Nothing.
Not a damn thing. No spark. Rotor is spinning. What next? I am stumped.
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coil wire? Crank position censor?
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Replaced coil wire. Cps? Not yet
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when you crank it do you hear the fuel pump? do you get 12v at the coil (when you crank it)?
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Eliminated fuel with starter fluid test. Got a new cps. Putting it on now.
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What am I missing? Ecu?
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What's the year and model?
My friend's Cherokee did a similar thing, ended up being a ground problem to the PCM.
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95 yj with 2.5
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Eliminated fuel with starter fluid test. Got a new cps. Putting it on now.
that doesn't mean anything, you might not have spark nor fuel. Without any tests is hard to tell unless you want to troubleshoot by replacing items.
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Poured fuel down intake. Not so much as a pop or crackled. Spark? Tough
to check by yourself. But. From what I see no spark.
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With the help of neighbor he cranks I checked for spark. Nothing. I checked power to the coil. Nothing. Still stumped. What's left?
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Time to get out the VOM or test light. You didn't saw how long it idled for before dying either. It sounds like it's going to be either two independent issues or a bad ground or PCM. You're going to have to test for each.
- Check for stored codes in the PCM?
- When you turn on the ignition does the seat-belt and CEL turn on and then turn off?
- Instead of just bypassing the fuel pump, listen for it.
- Check the Camshaft Position Sensor in the distributor?
- Check all of the fuses in the PDC?
- Check all of the relays in the PDC?
- Check the ground on the PDC (6BK)
- Check both grounds on the PCM. (#11 & #12 16BK)
- Check the signal ground on the PCM. (#5 16BK)
- Check the coil driver on the PCM. (#19 18GY)
- Check the Relay Coil signal on PCM. (#15 18DB/YL)
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Let it idle for a minute. It died sharply no stuttering. No codes. The seat belt light comes on and goes out. Check engine light no not at all. Cannot hear pump but never could. Will listen tomorrow. Fuses in pdc are all good. Have a different pcm/camshaft position sensor arriving tomorrow. Will run test then. Thanks
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Let it idle for a minute. It died sharply no stuttering. No codes. The seat belt light comes on and goes out. Check engine light no not at all. Cannot hear pump but never could. Will listen tomorrow. Fuses in pdc are all good. Have a different pcm/camshaft position sensor arriving tomorrow. Will run test then. Thanks
check power to the ASD and fuel pump relay. If you don't have power to them then replacing sensors won't help, that's my guess - with the contact off you should have 1 prong with +12v, with the contact on you should have 2 of the relay prongs with +12v, if you don't check fuse 5 in the fuse block under the dash (left side of steering wheel). the Cam sensor will not give you spark or power to the coil, that's the crank sensor, the cam sensor only gives signal to synchronize the injector opening.
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Hmm no CEL and Brake light when starting up? I believe that's when the PCM goes though it's diagnostic.
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Asd? What is this?
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Left key on for a few minutes. No codes.
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Left key on for a few minutes. No codes.
Left the key on? If your not getting a CEL and Brake light when you turn the ignition on, I would suspect the PCM. It's supposed to go into diagnostic mode when it stars up.
Also, you should always get some type of code. You'll get a 12, 33 and 55 always. If you're not getting any codes then I suspect the PCM is FUBAR.
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Are you sure you are checking for codes properly? (cycleing the ignition switch 3 times)
By the way great responces on this post.
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Hmm no CEL and Brake light when starting up? I believe that's when the PCM goes though it's diagnostic.
if circuit G50 has no power when the key contact is on (key in run position) then the PCM won't go into startup mode, that's the same circuit providing command 12v to ASD and Fuel Pump relays, so he should start by checking that first (it's fuse 5 in the fuse block)
Asd? What is this?
ASD Relay = Automatic Shut Down relay, is the one that sends power to the coil and fuel injectors while the engine is rotating.
Do the tests i suggested, you might save some money (i'm not saying is not the PCM but you should check this first).
EDIT: the gauges are powered from fuse 9 and both fuse 5 and fuse 9 are in turn powered from the same circuit coming from the key contact. If your gauges are not working with the contact in the run position then could be a problem with your contact, if they are working then check fuse 5 and see if it's fine or not, if it is check the power at the ASD and Fuel Pump relays - if you have 2 prongs with 12v (on each of these 2 relays) with the contact in the run position then you have a different problem (and could mean the PCM is fried but you can't tell for sure), if there's only 1 prong with 12v then it's an electrical issue which you should fix before buying more parts.
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if circuit G50 has no power when the key contact is on (key in run position) then the PCM won't go into startup mode, that's the same circuit providing command 12v to ASD and Fuel Pump relays, so he should start by checking that first (it's fuse 5 in the fuse block)
Yeah, I was looking at the schematic and saw the ASD connected to the fuel pump. Thought about it but didn't say anything. Figured you'd mention it. :lol:
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Yeah, I was looking at the schematic and saw the ASD connected to the fuel pump. Thought about it but didn't say anything. Figured you'd mention it. :lol:
:thumb:
same circuit that goes to PCM pin 9 also
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Where is asd? In the pdc labeled as fuel?
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Where is asd? In the pdc labeled as fuel?
location "E" in the PDC (NOT labelled as fuel), next to the starter relay
fuel pump relay is in location "B"
the relay slots are lettered from A to G starting at the end with the lock for the cover on the PDC (not the hinge side)
did you check fuse 5 in the fuseblock???
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All fuses are good. Gauges have power.
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All fuses are good. Gauges have power.
check the power at the relays then, here's a diagram that would help
(http://i57.photobucket.com/albums/g222/sharpxmen/Misc/PDC.jpg)
the 7 and 22 locations will have 12v at all times (contact off as well)
6 and 21 should have power once you put the key contact on (in the run position) and should also have power when you crank it. check these to make sure you have power.
Once you check these you should check to see if you get command ground on those 2 relays when you crank the engine (cavity 10 on the Fuel pump relay and cavity 25 on the ASD relay). If you don't you can also check pin 9 at the PCM connector (white with yellow stripe wire) also so you know the PCM gets signal for run mode if the relays turn out to have the proper power but no command (ground) signal when you crank the engine.
At this point if you get proper power and ground command signal the problem would be one of the relays (most likely the ASD), if you don't get proper power then trace the problem. If you have power and no command ground signal when you crank the engine check at the PCM on pin 3 (red with white stripe wire) you should have +12v permanent (at all times even with the key out of the contact).
Once you check all these report back and we can move onto checking the voltages and signal at the crank and cam sensors, but let's make sure you have proper voltages on the obvious ones first.
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The check engine light should turn on as a bulb check as soon as you start to turn the key. This does not depend on anything else, no sensor inputs, nothing, just a bulb check. So, if it does not turn on it is either: 1) the bulb burned out, 2) the PCM has a bad connection, or 3) the PCM is bad. I went through this not too long ago and in my case it was the PCM. I don't have the info here right now but the key is to check power and voltage to the PCM. If it has power and voltage and you still don't get the check engine light then it is almost completely certain the PCM is bad.
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Preformed all the tests suggested. Andy showed with a new ecu. Everything workd now. Thank you. The list is a great it was a big help.
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Preformed all the tests suggested. Andy showed with a new ecu. Everything workd now. Thank you. The list is a great it was a big help.
so was the ECU dead?
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Yes as soon as it was plugged in the cel lit up. The new Ecu weighed about twice as much as old one. Why?
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You might want to keep the old one and open it up and see if you can fix it. Most of the time it's those capacitors that go bad and they are cheap to fix.
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Good to hear you solved it.
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Yes as soon as it was plugged in the cel lit up. The new Ecu weighed about twice as much as old one. Why?
what? they're all the same for 91-95, cant see why that was unless it was a reman
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LOL they are "Supposed" to be all the same....
We need to start a data base of numbers off of them as well as where manufactured and any other external data.
Bet we find some differences based on factory of production and month built especially 94 and 95.....
The BMW list I'm on has this (BMW actually publishes it!!) and its huge when troubleshooting...
Dave