rockola1971
Full Access Member
If you believe him then grab a BCM that matches yours as close as possible. They arent expensive at all at salvage yard and ebay and are stupid easy to replace.
No start issues again
- Thread starter Phisher
- Start date
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He pm'd after this and had failed to mention in that post that the fuel pump relay has to be jumpered in order to get fuel, so my guess is by doing that it's flooding the engine and is probably not getting any spark (ecm/pcm) injector pulse cut-off.
rockola1971
Full Access Member
That fuse likely blew for a reason. Fuses blow when excess current travels through them thats higher than their rating. Excess current is caused by a partial short to ground, dead short to ground or excessive load for the circuit. I would disconnect whatever is blowing the fuse since the aim here is to troubleshoot the no start issue and there is no sense in throwing another monkey wrench into the main problem.
It sounds like you have no spark or jumped time. Pull spark plug out and verify a nice bright blue spark. It should not be lazy orange/yellow. Battery has to be charged up to get a proper reading on the spark situation.
OP
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Phisher
Member
Yes the fuse blew because I touched ground and constant accidently when I was taping off all the wires that were cut from the stereo so here will start fresh again.. so new fuel pump new fuel filter engine turns and turns and turns but does not start if I spray it with starting fluid still does not start the only time I have power going to the fuel pump is when I stick a wire and pin 30 and in pin 87 to jump them together otherwise if the relay is in I still have nothing so what I'm gathering from you guys is I should start taking plugs out one at a time to see how they fire I also went and purchased a test light I'm going to start checking negative connections and positive connections and seeing if maybe there's a crown so you guys win you convince me to keep the beast for another day LOL thanks again guys
rockola1971
Full Access Member
Yup. My guess too. No spark or jumped time. I would verify spark then if no spark I would look for 12 volt reference voltage and passlock signal going back to BCM in the below schematic. But it sounds like Pass Lock has been programmed correctly.
The having to jump the fuel pump relay should be easy enough to trouble shoot and could be related to the rest of the mess or is a totally unrelated problem.
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rockola1971
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We will get this thing running correctly. You just have to be patient with the Yukon and us.
Fuel pump is useless if no spark so we will worry about that later. It could be related to the cause of no spark if thats whats going on. Ignition coils are all independtly controlled by different connections to the PCM. For right now pull one spark plug and check it for spark on all cylinders driver or passenger side (dont matter which).
Check your INJA and INJB fuses(Both 15a fuses). One feeds your even cylinder injectors AND IGNITION COILS and the other feeds the opposite side. If one or both of those fuses is blown it will cause your mess.
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rockola1971
Full Access Member
ECMB Fuse (20a) is the feed to your fuel pump and since jumping the contacts makes your fuel pump come on that tells me that part of the circuit is fine and your problem lies in the control part for that circuit which is the fuel pump relay coil and its feed. Coil is fed by pin 9 Connector 2(Red) of PCM. Check for 12v while cranking at relay socket and also check to make sure there is continuity from the ground terminal in the relay socket to chassis ground. Measure resistance across relay coil on relay itself also. Could just be a bad relay. It is also possible that the relay contacts are burnt and will no longer pass current but are closing. (Thats a whole different check).
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Phisher
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I will do that I'm also going to just take a short video of what is going on before I start doing anything and I'll post it here so people can listen and see but right now I'm at a parts store I'm going to pick up a spark plug tester and a compression tester and then I'm going to grab a new multimeter that way I can test my positive and negatives throughout
MassHoe04
Full Access Member
Compression test might be good information to know at some point, but I would think that you would hear it trying to fire-off. Even if several cylinders had poor compression it would get somethin poppin off. Would not be pretty, but you would still have something happening.
If compression were a factor, it would kind of start. You might notice blow-by. Or... in an extreme case of blown rings, maybe even raw fuel in your oil pan.
Not sure I would fixate on compression testing in trying to diagnose your particular issue. But I could be wrong. That is just my thinking.
If compression were a factor, it would kind of start. You might notice blow-by. Or... in an extreme case of blown rings, maybe even raw fuel in your oil pan.
Not sure I would fixate on compression testing in trying to diagnose your particular issue. But I could be wrong. That is just my thinking.
His vehicle most certainly can be bypassed by using an appropriate resistor between the tumbler and the signal wire to the BCM, given the disconnected yellow wire he found inside the clamshell that is very likely what his "repairman" tried to do.
The resistor in the key system was replaced by a permanent resistor in the tumbler that made the connection as the tumbler rotated; even the resistor range stayed the same until at least 2007.
In 2002 the factory ECM even refers to the security system as VATS in the section where you can disable that garbage system.
