"Click" no start..

[brandon_mchenry-mt]

2018 Tradesman 2500 6.7l Cummins 4x4, 86k miles

I am having this same issue, after a cold night or extended sit in cold weather “click” no start. Occasionally it will start after 5-6 attempts.

If I remove the starter solenoid relay and jump the pins using a paperclip, it turns right over and starts up. No struggles/rough warmup as if the block was cold, indicating the block heater is functioning.

Last year the engine block heater and one battery went bad, I replaced both batteries and the engine block heater. Additionally, I replaced the starter solenoid relay thinking it might be the culprit, no joy.

Every once in a while i do get the ETC warning light but turning the truck off letting it sit for 30 seconds (doing nothing else) and restarting usually corrects that.

Things I know it is NOT:

Starter
Solenoid
Solenoid relay
batteries
block heater
grid heater

Any other ideas?

 

[H3LZSN1P3R]

Batteries need to be tested

 

[brandon_mchenry-mt]

Batteries need to be tested

The batteries are good, I tested them myself. Electronics tech, have my own voltmeter and other test equipment. They are less than a year old and are very good AGMs. 12.5v static, 14.5v running, 900CCA (cold cranking amps).

 

[Great White North Eh]

So you load tested them?

 

[brandon_mchenry-mt]

I don’t have the equipment for that but watching them on scope during the starter solenoid relay jumper process them are very stable, I don’t see an issue with the batteries at this time.

This seems to me a problem somewhere in the electrical chain. The mechanical chain is solid. What exists between the ignition and the solenoid relay block that would disrupt signal?

 

[H3LZSN1P3R]

Are your battery cables and terminals all clean and tight? Whats the amp draw when starting? (assuming you have an amp clamp to use)

 

[brandon_mchenry-mt]

Are your battery cables and terminals all clean and tight? Whats the amp draw when starting? (assuming you have an amp clamp to use)

Yes and yes, amp draw 428

 

[gimmie11s]

Batteries....

The cold weather produces threads like this every single year.

 

[PRS]

So, on pin 85 of the start relay you should have battery voltage coming from the BCM. The PCM applies a ground on pin 86 when you try to start. You know the connections on the other side of the relay are good because the paper clip works. Test for voltage at pin 85 and ground at pin 86(of the relay) when you select start. Whichever is missing will point you to the problem. Use a test light, as a voltmeter may show voltage but a poor connection upstream won't allow current flow and the voltage will drop. Same issue with the scope.

Also, and I don't have anything in this but to try to help, Mitchell DIY has a very good procedure for troubleshooting this, to go along with some very good wiring schematics. The cost is reasonable as well.