Hello, can anyone tell me what wire are hot that come out of ignition switch. Start, Run Acc. Replace CPM still no start
04 Trailblazer no crank no start
- Thread starter Trchamp
- Start date
Here ya go:
RED on the ignition switch is 12V, fused by underhood fuse #34, and feeds the following three circuits:
White is hot in ACCY, RUN, START
Orange is hot in RUN
Yellow is hot in START
RED/WHITE is another 12V, fused by underhood fuse #36, and feeds two circuits:
Brown is hot in ACCY, RUN
Pink is hot in RUN, START
If you could describe in more detail the behavior, many of us can chime in with a better list of the other 100 things it might be. For instance, any codes, maintenance history, mileage, do you hear the fuel pump priming the line pressure, does the starter relay click, does it turn over and not catch, do the headlights come on in RUN and go off in the START mode? That sort of thing.
RED on the ignition switch is 12V, fused by underhood fuse #34, and feeds the following three circuits:
White is hot in ACCY, RUN, START
Orange is hot in RUN
Yellow is hot in START
RED/WHITE is another 12V, fused by underhood fuse #36, and feeds two circuits:
Brown is hot in ACCY, RUN
Pink is hot in RUN, START
If you could describe in more detail the behavior, many of us can chime in with a better list of the other 100 things it might be. For instance, any codes, maintenance history, mileage, do you hear the fuel pump priming the line pressure, does the starter relay click, does it turn over and not catch, do the headlights come on in RUN and go off in the START mode? That sort of thing.
I drove it home and it was fine. When i went out Monday morning when i turned the key nothing happened. So i replace the ignition one from Napa same problem. But i did notice the back up light did not work when you put in to reverse. But when you unlock doors with remote they do come on. The gas gauge is not working properly and the gear shift light on dash under pnd isn't working. I checked all the fuses. I also jumped starter relay by grounding relay motor turns over. Jump fuel pump relay and fuel pump runs. I think the next thing is to check wires on ignition switch. I did try a used pcm with no luck. What about the passlock? do they go bad. My wife drove the car up to a week ago and she has alot of keys on her ring and i only have about three keys. I also checked all the grounds. It looks like there is one under fuse block under hood?
the roadie said:
It has 97,000 miles on it we did try a scan reader and it would not talk to it. the check engine light does not come on when you turn the key on. it was on for awhile.
When you checked all the fuses, you might have missed some in the rear fuse block, or front fuse #13 that runs the accessory outlet plus the code reader connector. Check that again, and get a code reader to see if there's a code now. If the gear shift indicator is dark, that's just a gauge cluster problem, but if it's not reading properly, and the reverse light switch is not working, you may have a problem down on the transmission with the park/neutral/gear mode interlock switch and that could be your starting problem. Recommend downloading the manuals here or buying the Chilton's if you're going to troubleshoot this more yourself. Do you have access to a lift or jack stands and heated garage?
I was under it and replace the neutral safety switch. i did notice when my friend was jumping the starter when i moved the shifter out of park it did stop turning over. It I think the cpu is not getting power or something. I will get a good scan too tomorrow. checked fuse 13 fine. any thing else i could check.
the roadie said:
I check the voltage at the ignition switch and i have battery voltage on all wires on run and run start. The bell that ring some time stays on when i remove key.
NinjuhhNutz
Member
- Oct 15, 2012
- 720
not to beat a dead horse, but mine was driving me up the wall trying to figure out a problem that was quite similar...turned out that I had completely missed fuse #31 which is almost hidden in the top right corner of the fuse box (if you're on the driver side over the fender) I was absolutely livid when I realized I had wasted so much time and had overlooked the same thing multiple times...may not be your problem, but *fingers crossed* for an easy fix
Every Fuse is perfect. Front and in back. I did see online someone had same problem and he took it to the dealer and they told him that he was not getting power to passlock. Open circuit #440 does anyone have a diagram of this circuit.
NinjuhhNutz
Member
- Oct 15, 2012
- 720
There's a link to wiring diagrams on on forums page, when I get home I'll shoot you a link to it...pita to do it on my phone here lol
Sent from my SCH-I510 using Forum Runner
Sent from my SCH-I510 using Forum Runner
The manual says circuit 440 is battery voltage from the fuse block to the instrument panel. I don't see it being involved in the Passlock system, which is a three wire connector (12V, ground, and sensor data) going from the key cylinder area to the BCM.Trchamp said:
the roadie said:
First Thanks for all the good data. Here is what i found out .Put a tech 2 scanner on it and we could not talk to cpm but we could talk to the BCM it said u1000 class 2 data malfunction. I put a used cpm no change. when you turn the key to start then to run the surcurity light goes off then comes on and stays on.
Trchamp said:
Did you go into the class 2 section and see if any other module reported losing communication with the pcm?
I remember a similar case not too long ago where another member lost pcm communication due to the pcm losing one of the B+ circuits. Allegedly there was a break in one of the wires that go to the pcm. IMO it would be worth verifying powers and grounds at the pcm next.
MAY03LT said:
I do have a print out of the pcm but the wire colors dont match. is there one for my 04 trailblazer that i could use to make sure i have power to the pcm?
Pin number 20 on blue plug on pcm wire was broke orange wire. One foot down from plug behind tape. No power to computer. Cir 440. Thanks Everyone.