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Mike S.
Mike S., Mechanic
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Experience:  25+ years experience as an auto mechanic.
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My car does not start at times usually first thing in mornings, when I jumper the starter

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My car does not start at times usually first thing in mornings, when I jumper the starter relay it will start every time. Once I drive it, it usually will start through the day, but not always. What causes this? There are no codes given when it does not start. All lights work, battery is good, no circuit going to starter when it is not starting, again if I jumper the starter relay In the fuse box under the will start.

Ok, taking a look at the wiring diagram, click here, you said you are jumping the relay.

That should mean that the battery cables are fine and the grounds. If you are also getting power for the jumper at the relay, then that means the fuse IGN 2 and that circuit is also ok. Is this true? Are you grabbing power for the jumper at the relay?

If so, that only leaves pink wire and yellow/black as the culprit or anything on either of those circuits. The next time this no crank happens, before you jump the relay, text for voltage at the IGN Main 1 fuse #27 in the underhood fuse block with the key on start. Let me know and if it's a no voltage follow the diagram back and test for voltage at the IGN 3 fuse 19 which should be hot all the time. If the IGN Main 1 fuse 27 does have voltage then the problem may be exiting the elay on the ground circuit, so with the key on start jumper that yellow/black wire to ground and listen if the starter cranks.

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Customer: replied 4 years ago.
Yes I get power from relay, using a small piece of wire. It will start every time when I do this. The car at the present time is at my car repair man. It has not failed to start for him all week. I told him that if it does not act up by Monday, I will take back home and keep record of times it will not start. It does not make since to me, as when it sets at my house it acts up almost every morning but not always. I will keep your answer open and get back with you the first of next week. Again when I try and start with key is when it acts up. At this time I will leave it in the on position, jumper the relay and it starts. This does not happen all the time that is why I would think it is some type of electronic device that is acting up. Thanks keep me informed of your recommendation and I will get back with you.
Then the problem must be exiting the relay on the ground circuit, so with the key on start jumper that yellow/black wire to ground and listen if the starter cranks.
Customer: replied 4 years ago.

So in order to jumper that yellow/black wire, How do I get to it. Do I remove the relay we are talking about. and instead of jumping relay, jumper form yellow/black side to ground. Where do I ground it? Do I have to take the fuse back plate off. I am just learning on troubleshooting and this will be a learning issue for me. I will get the car back to day maybe instead of next week. Please give me a Code so when I want to ask more questions I can get you each time. If I find this a good answer you will have a friend for life. I have two vehicles this one and my 2004 K2500 Avalanche.

just leave everything hooked up as normal jumper that yellow/black wire to ground, then turn the key to start. Ground it anywhere to a good clean metal ground. If you cannot find the wire there it's going to the pin 76 on connector c2.

In the future, you can reach me through my profile page,

Customer: replied 4 years ago.

Is the C2 Located under the hood? Does the Crank REQ signal that goes to the ignition switch required for both the Start or Run position. Meaning if it starts by jumping at the Crank Relay. It would not be the Powertrain Control Module? Would I be wise to invest in a probe lite for testing for power at some of these wire? Also for future trouble shooting? I will get my car back today and let you know what I find out.


You sure have alot of questions without even having the car back yet. Let's just take it one step at a time.
Customer: replied 4 years ago.


Do to my job, I can't get to this troubleshooting again until this weekend. I would like to have the extension of time for this problem. But can we wait until this weekend to start. In the mean time you can be thinking about what I would have to do to check in the key area on the column. What would it take to replace the ignition or the natural switch. I think there is some then worn in this area of the car.


Thanks Frank.


Ok, until this weekend.

Why do you think there is something worn around the key area?

Customer: replied 4 years ago.



Today is Friday, I will be able to test some of your recommendations this weekend. I just to need it to happen. I think it is in the key or safety switch. Some times when I get in and try to start it when in park nothing happens. When I move it to the neutral position it will start. Other times nothing at all happens. I was wondering if there is an adjustment that can be done to the safety switch. Where is it located?


Thanks will check back later.



Some neutral safety switches do have an adjustment. I will look this one up.

Try this the next time nothing happens when turning the key. Hold the key on start and move the shifter all the way from park to low and back and forth a few times listening for any spot where the starter engages, if it's any spot except park and neutral, either the neutral switch needs adjusting or it's faulty.

I don't see an adjustment so if it's at fault, most likely replacing is what to do.
It's called a transaxle or transmission range switch and it located on the transaxle or transmission.
Customer: replied 4 years ago.


I want to thank you for your patients on this issue. I tried to start it this morning and it would not start. I wanted to see if I was getting voltage at the input of the Starter Relay on the Coil side and the terminal side and I was. I did not move the shifter or anything in the car. I just removed the relay. Put a small thin piece of aluminum metal part in each of the terminal side (input and output) this was so I could test to see if the voltage was going through the relay and the coil was energizing. I put the relay back in with a tip of pieces sticking out so I could test. Not doing anything else I try to start the car and again and it started. It now starts for me, so I can test anymore again. I will have to keep your notes on file and once it does it again I will try again. I am also going to close this answer as finished. I will continue to test and see if I can come up with a few additional results. Once I do I will get back to you. In the mean time I will keep your contact on file for the next issue. Thanks for all you did for me and sticking with me.


ok, Thank you.