No Ignition

[wipeout]

I have a 2000 montana 3.4L, with no ignition. I have checked power going to the ignition module, it has power for a few seconds then cuts out. I Checked the fuses and relays, all seem to be ok. Im unsure where to go from here. Any help would be appreciated.

[wipeout]

I have no spark anywhere. There is no voltage coming into the ignition module. I unpluged the power/ground wire going into the ignition module, using a 12 volt test light I test the power wire by turning the ignition key to run , the wire powers up for approx. 3 or 4 seconds then shuts down. It seems like a relay is shuting it down.

[Selectron]

I'm not familiar with your vehicle but I had a look at the wiring diagrams on the autozone website (Repair Info section).

The electrical path to the ignition module appears to be fairly straightforward. Starting out at the top left of diagram 1 (below), 12V is available at the 'IGN 1' terminal of the ignition switch when the switch is in the Run, Bulb Test, or Start positions. Follow the path down through the PCM/ABS fuse (10A) to the IGN MAIN relay - and that's the coil side of the relay rather than the switched contacts:

Diagram 1

Pick up the coil side of the IGN MAIN relay again at the top left of diagram 2, and note that the low end of the coil has a constant connection to ground, so therefore the relay will activate whenever the ignition switch is at Run, Bulb Test, or Start.

Now look at the switched contacts side of the relay and note that the 12V input is hot at all times (top of diagram), so when the relay is activated it will feed that bank of five fuses, amongst which is the ELEK IGN fuse (15A), which in turn leads to point 'K':

Diagram 2

Point 'K' at the top right of diagram 3 then feeds the ignition control module:

Diagram 3

Finally, at the top right of diagram 4, the ELEK IGN fuse can be seen feeding into the ignition control module via a pink wire, which presumably is the point at which you're checking for voltage with the test lamp:

Diagram 4

If the diagrams are accurate then tracing the voltage should be reasonably straightforward - unless the wiring has been modified, for example by adding an aftermarket security system. If you have voltage for a few seconds then all fuses must still be intact so I'd concentrate on the relay, which might have worn or dirty contacts or a faulty coil. If you have an identical relay elsewhere on the relay panel then you might want to try temporarily swapping them to see if you then get a constant voltage at the ignition module (ignition switched off while you swap them). If the symptom remains the same then swap the relays back again and start tracing the voltage to see at which point it disappears.

And if the above links don't work then try these instead:

Diagram 1 Diagram 2 Diagram 3 Diagram 4

[wipeout]

Thank you for the indepth response, it should be very helpful, I hope.
I did swap the relay with no luck. Could it be the PCM?

[Selectron]

According to those diagrams, no - the 12V feed to the ICM is a standalone circuit over which the PCM has no control. I know nothing about your vehicle though so there might be other factors not shown on those diagrams which I'm not aware of.

With the ignition switched off, I would unplug the relay and then probe for voltage into the now-empty socket terminals. With the ignition still off, the socket terminal corresponding to relay terminal 87 should have 12V at all times - that's the way it's shown on the diagram but if you don't find 12V on 87 then check on 30 instead (the terminal numbers should be marked on the relay casing).

Then switch the ignition to the Run position, and the socket terminal corresponding to relay terminal 85 should now have a steady 12V. If you don't have 12V on 85 then try 86 instead because the relay coil can be wired either way around, but one of those two should have 12V at Run.

In a nutshell, what you're looking for is to verify that one socket terminal always has 12V (for the relay's switched contacts), and one other socket terminal has 12V only when the ignition is in the Run position (for the relay coil).

The results from that should tell you whether the 12V feed (to the ICM) is being interrupted before or after the relay. Not sure where to go next, but that would be a step forward at least.

Edit: Just had another thought - is it possible your battery is flat? The voltage might be high enough to pull the relay in, but then when current starts to flow, the voltage might be dipping below the relay coil's drop-out voltage, at which point the relay would drop out again. If there's any chance of that being the case then it would be a good idea to hook the battery up to a charger before going any further.

[RahX]

GM is notorious for the ignition module going out. It is the thing that all the coils are going to. You would be better off going to the pontiac or chevy sections and doing a bit of research. The relay doesn't stay on unless it sees RPM, coming on and shutting off is normal. Try checking for power with it cranking, i'm sure you will see it the whole time it is cranked.

[wipeout]

The bat. is fully charged and I think I did check for voltage to the ICM with the engine cranking but I will check again. I will also check the relay socket terminals.
Thanks

[wipeout]

So i checked the socket terminals and one allways had 12V with the ignition off and one has 12V when the ignition is in the run position. Everything checks out so far, so then i tried testing for continuity from the pink power wire coming from the ICM. I had continuity on 3 of the socket terminals, but the way i understand the schematics only one should have continuity. I also tried cranking the engine over and checking for voltage at the ICM and there was none. I was also considering that the ignition switch is possibly faulty, but when i switch the ignition to the run position i have voltage on the one socket terminal. I am not quite sure what to think and could use some more feedback. Thanks

[Selectron]

Voltage conditions at the relay would appear to be normal then, so there will be a constant 12V available from the relay's switched contacts, which is to say that the interruption is happening after that point.

We know that the path between relay output and the ICM must be intact because you do see voltage for a few seconds at the ICM. That would suggest that there's something between the relay output and the ICM which isn't shown on the wiring diagrams - something which is capable of interrupting the path, such as another relay perhaps. If you have an aftermarket security system fitted then that would have to be suspect. If it's a relay then you might be able to locate it by listening closely both under the hood and under the dashboard for a click after those three or four seconds.

If you can't hear a click then you might want to take a closer look at the Underhood Accessory Wiring Junction Block shown on diagram 3, and see if there would be any possibility of tracing the pink wire which feeds the ICM, and see where it leads to, or trace it back in the opposite direction, starting at the ICM. If that isn't a practical proposition though then you'll likely need some input from somebody who is familiar with the vehicle and its ignition module.

[wipeout]

There is no aftermarket secuity or anything else aftermarket, I purchaced the van from new and it has been a problem from the start.
RahX says the relay doesn't stay on unless it sees RPM. On diagram 4 the crankshaft position (CKP) sensor (7x) goes into the ICM which in turn goes into the PCM. So the PCM must shut the relay off if it doesn't see the CKP?

[dewaynep]

Are you backprobing the wire at the ICM connection or do you have the connector disconnected? It's possible there is a sense circuit wire in that connector that has to be connected.

[lesterl]

Does you key have a rubber head and PK3 stamped on it?

[wipeout]

No im not backprobing the wire, i have the wire unplugged and am checking it that way. So tomorrow i will try backprobing the wire and i will let you know how i made out.

[wipeout]

The Haynes manual i have says to disconnect the power/ground electrical connector from the module and check for power at the pink wire terminal, it says there should be voltage with the key on.

[RahX]

Listen, go to autozone and pick up an ignition control module. I used to replace those things all the time. Don't bolt anything down, just set the coils on it and plug it in and see if it works. If it doesn't, take it back. Tell em you're taking it to a shop and that you don't need the part . If you had a scantool, you could check cam/crank signals a lot easier. They produce AC voltage so you should be able to use a DVOM and see if you get anything out of either.