Intermittent no crank no start

Vince Technician Glendora, California Posted   Latest  
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Driveability
2008 Buick Enclave CX 3.6L (7) 6-spd (6T75)

I have an Intermittent no crank no start on a 2008 buick enclave, according to the customer these are the symptoms. Vehicle has not acted up since looking the vehicle over. battery tested and passed, charging system and starter also tested and passed. also no codes.

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Edward Owner
San Antonio, Texas
Edward Default
 

Vince Try doing a flood mode test to see if the starter acts up...

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Albin Diagnostician
Leavenworth, Washington
Albin Default
 

Have you studied a wiring diagram and the theory of operation for the starting system? Any volt drop testing of the starting circuits?

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Randy Diagnostician
Glendora, California
Randy Default
 

I would current ramp starter with your scope in clear flood mode . And see heath of the starter and circuit. And did you load check battery ???

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George Owner/Technician
Mobile, Alabama
George Default
 

No crank covers a lot of problems.....If the starter attempts to crank but does not have enough power to turn engine over could be open comm bar and when armature stops turning the open comm bar may stop on one of the brushes which would give you less torque & RPM's Ask customer if the solenoid makes a loud clicking sound ?

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Vince Technician
Glendora, California
Vince Default
 

Customer said it didnt click nor crank at all.

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Vince Technician
Glendora, California
Vince Default
 

I did load test battery & it passed its only 1 year old. also did a starter amperage draw test & it also passed. Going to try the flood test on starter.

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Vince Technician
Glendora, California
Vince Default
 

loaded the battery with a carbon pile tester and it passed, battery is 1 yr old. also did a Amperage draw test on starter. will try the flood test on starter. ty

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Edward Owner
San Antonio, Texas
Edward Default
 

Albin, on the fly upload

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Lorenzo Diagnostician
Collinsville, Oklahoma
Lorenzo Default
 

Engine compartment fuse box has three bolts that are usually overtighten and stripped. This causes intermittent engine/electrical issues with bad connection or damaged terminals.

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Rusty Owner/Technician
Oakham, Massachusetts
Rusty Default
 

This may seem “way out there” but I was called in to diagnose a Buick 3.6 of that era that had an intermittent no-crank but the shop could occasionally duplicate it and discovered no PCM communication with a scan tool when it wouldn’t start. they would jump the starter relay and it would then start and run normally and restart again normally with the key till it went through a cold soak. I…

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Dave Mobile Technician
Ironton, Ohio
Dave Default
 

I have seen the same thing on several vehicles with the Boshe pcm. Sometimes you can just momentarily touch the starter relay wiring at the pcm with a grounded test light and they will then crank from the switch.

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Sean Owner
Hamilton, Ontario
Sean Default
 

Look for the grounds Around the engine bay that are loose or damaged. Try using a jumper cable, introducing a secondary ground to body and ground to engine.

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Darren Mechanic
West Allis, Wisconsin
Darren Default
 

don't touch anything until you get it to act up. Everything else is just a guess. Rule 1, duplicate customer complaint....

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Mohammadu Diagnostician
Auckland, New Zealand
Mohammadu Default
 

Vince, first test the power present on the starter 50 Terminal when you crank​.​if not check the starter relay there should be one ground and one power and power from starting switch (Ignition switch) (key). I would normally try to energise the starter first on this matter.

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Douglas Technician
Hermon, Maine
Douglas Default
 

Check pins 6 and 14 at dlc for 60 ohms of resistance on the high speed network. Leave dvm hooked up for the next step. (I’ve seen the rear differential clutch wiring harness chafed in the left rear wheel well) Wiggle the rear diff clutch harness where the harness gets flat near the subframe in left rear wheel well. When this acts up it takes out the high speed network, no start no run.

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Vince Technician
Glendora, California
Vince Default
 

This model is not AWD dont see a rear diff, or harness. but still will check the pins you mentioned ty.

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Bryan Owner/Technician
Sylacauga, Alabama
Bryan Default
 

Lot's of possibilities. Without symptoms present, any repairs will be a guessing game. I have seen sunroof leaks wetting the fuse panel above the passenger footwell cause a no start. Any signs of moisture inside?

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Phillip Diagnostician
Anchorage, Alaska
Phillip Default
 

When I load test a battery I do it in the customer condition for the no start. Example. It was -10 or lower in anchorage in January. We had a lot of people complaining that car would not crank. Other people in the shop would just do a carbon pile tester in the shop. A alternator, battery & starter test, the battery would pass. Parasitic draw test would pass. Customer would come back…

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Fred Owner/Technician
Santa Barbara, California
Fred Default
 

Read an article recently about a strange no starting GMC due to a Right side Object Detection sensor going bad, try a full scan, hopefully something will show up.

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