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CCTMSTR, GM Certified Master Technician
Category: GM
Satisfied Customers: 395
Experience:  GM Master Technician.ASE Master.Advanced Level L1. NV State G2 Emission Inspector
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2002 GMC Sierra 1500: starting problem..V8..Start position..indicator

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Hi I have a starting problem with my 2002 GMC Sierra 1500 truck. 5.3 V8 The battery is New and not run down. When turning the Key to Start position it goes dead and the prindle indicator goes dark. I have tapped on the starter with a small hammer while trying to start, again nothing. I have put the shifter in neutral, again nothing. I am thinking the neutral safety switch. Any help welcome thanks

It sounds like you have a voltage drop at the ignition switch.Do you have a volt meter or a 12 volt test lamp to perform some checks?

Customer: replied 8 years ago.
Yes I do. I am very familiar with electrical and mechanical work. I do it for a living. Also the problem is intermittent. It seems to do it after the truck sits for a day or two without being run. thanks
It's best to access the wires at the ignition switch,but under the dash there is a large multi wire connector (c201).Check for battery voltage on the 10gauge White,Brown,Pink and Red with the ignition key turned to the ON / RUN position.Anything less than battery voltage indicates an Ignition switch failure. Very common.
Customer: replied 8 years ago.
I will do that thanks. A bit more info for you. The truck will start after numerous tries. One time it started after about 8 tries, other times it takes longer. If it is my ignition switch are there any othe symptoms to look for? THnaks
It would depend on what circuit is affected, starting in 3rd gear, (PRNDL) lights going out.stored fuel control dtc's (relay or various evap codes).You could also check voltages at the underhood bussed electrical center fuses.They would also show low voltage if the ignition switch was defective.
Customer: replied 8 years ago.
Hi I cannot locate the wiring under the dash you referred too. But I have checked my voltages in the fuse center under the hood. They check out OK. I will say the first time this happened, the 40 amp fuse, position top left looking at it from driver side fender, blew. After replacing it the truck would not start. the truck did start after many tries after that. The fuse has only blown the first time this no start issue began and no fuses have blown since. I have also swapped out relays in that same fuse center under the hood without success. thanks
Does the veh start now?
Customer: replied 8 years ago.
No, this is the longest dead period I have had so far. I also checked the reverse lamps. They are working properly, key in run position and shifter in R. Here is more info. Foot on Brake attempt to start, Prindle goes dark and 2Hi, 4Hi 4lock, lights all come on briefly and I hear a rely type sound that resets them to 2Hi lit only. The head lamps and hi beam work also and are not dim. Thanks
With the key in the run position, give me voltage readings on the following fuses, 20 amp ECM B (under hood) and on the left I/P there is a cover to access the I/P fuses voltage on . IGN 1 and IGN 0
Customer: replied 8 years ago.
Hi Sorry it took so long. 20A ECMB under hood OK about 13 plus volts. When I plugged this fuse back in A hiss or small motor type noise under the hood, started and lasted about 2 seconds. It scared the crap out of me! FUSES IGN C and IGN A also checked out. The IP fuses were 10A and the voltage checked out OK there too,The door chime set off when I pulled IGN1. I also checked the fuses when they were out and all were good. I really appreciate this help. WHat next THanks
OK, at the transmission the drivers side, look at the neutral safety switch,tell me how many connectors are there. either 1 large or 2 seperate

Do you have a scan tool or code reader?

Customer: replied 8 years ago.
There are 2 separate connectors right beside each other one high one low.One more bit of info. Once the truck starts it seems to always restart while the engine ect are still warm. thanks

Have to tried to swap the starter relay? Do you have a code reader


Customer: replied 8 years ago.
I have swapped the relay in the past. I think there are 3 of them under the hood that are the same.One of them is head lamp relay and I know it is working. I'll go try it now. I do not have a code reader but if I get it running I can get it read at the auto zone near me.
Remove the starter realy check voltage at the cavities.Give me readings
Customer: replied 8 years ago.
Does the key need to be in RUN position or no key needed for the voltage readings
Key on
Customer: replied 8 years ago.
One of the four spade sockets reads 13V the others read 0V
First check the IGN C fuse for power on both sides, then check the IGN A (40amp). that starter relay should have voltage on (2) cavi

Starting w/o Dual Generator

Object Number: 776446  Size: FSties.

Sorry, one cavity voltage will be present during cranking
Customer: replied 8 years ago.
Ok, I agree with you after reading the schematic. One of the 4 has voltage. Thanks for the schematic. Any other ideas?
Customer: replied 8 years ago.
Ok, I agree with you after reading the schematic. One of the 4 has voltage. Thanks for the schematic. Any other ideas? I guess I can check the loop with the neutral safety switch by measuring the voltage at the socket of the starter relay socket when the key is in start position?
You can jump voltage cavity with the starter signal cavity with the key on it should crank
Customer: replied 8 years ago.
I'm a bit confused. First I checked the cavity that sends power to the coil of the starter relay with the key in start position. It IS getting voltage with the key in start position. NOW are you saying jump the two cavities that the starter relay would connect? If the vehicle cranks will it start with the key in run position? I assume I will need to remove the jumper as soon as it starts. Like a key start? Or should I try to jump the cavities with the key off first? Thanks

If there is power at all times on one cavity and power on the 2nd cavity during cranking you either have a bad relay,ground (G106) .Monitor circuit 3 the purple wire at the starter motor solenoid if you have voltage there your starter motor is bad.If you jump the starter motor solenoid circuit at the relay it should crank and start.if it starts remove the jumper.

Customer: replied 8 years ago.
OK I jumped the starter relay sockets with the key in run position and nothing happened. It must be my starter or solenoid. I looked at the starter from the bottom side and checked the hot always wire. it is HOT.
I am searching for the purple wire to the solenoid. I see a view of the starter through the inner wheel well. What is the location of the connection to the solenoid. top bottom side? What is the best approach to measure the solenoid for voltage. THanks so much. George

Object Number: 403977  Size: MF
Access through the right wheel well it will be the only small wire on the solenoid
Customer: replied 8 years ago.
Thanks I tried to read for voltage on the solenoid terminal when my friend hit the key to start. Nothing The starter relay is working I listened to it with a screwdriver to my ear. I also tried tapping on the starter with a rod and hammer through the side access while my friend tried t start it. No Success. It appears the problem is between the starter relay output to the solenoid, or the starter itself. I'm not sure I want to remove the starter myself. It appears there is a lot of stuff in the way. Thanks so much!!!!!!!!!!! ANy other ideas, let me know.I more than accept your help.

Check for voltage at the starter motor purple wire. if you have voltage during cranking and to engine won't turn over the starter motor is bad.


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Customer: replied 8 years ago.
Hi, I replaced the starter on my 2002 GMC today and it is working fine now. Thanks so much for all the help.