Hard Start, Like 1 Battery, Slow Spin.

[Gas Man]

10 degrees or less, not plugged in, wait till light goes out, turns over then slower and barely starts, new batteries cleaned terminals and they are charged, lights in cab all dim down, is it possible? has anyone had a sticky relay for the heater grid? acts like big amp drain, this morning I just waited about 5 sec for it to prime not for the grid to get hot and it seemed to spin faster, started right up, if I plug it in no problem at all, been doing this for about a year, had the charging system tested all ok, starting test ok, Truck has always been a great starter -15 sitting out for a week in the cold never exspected it to start and it always did, unlike my 99.5 ford. Has this happened to anyone else??? Am I heading in the right direction???

Thanks

 

[cerberusiam]

If you are SURE the batteries are good, load test them or you are not SURE, either replace the battery cable to the starter or start wacking ends off and putting news ones or terminals on them. The cables will corrode inside the cover and you cannot see it.

 

[Gas Man]

My next test, I have a good HD battery charged up and warm and a HD jumper cables is add this to the mix and see what happens, if it spins good? I also took the ground cable off on the engine block and cleaned everything up with a wire wheel.

 

[cerberusiam]

Usually it is not the ground cable, it is the starter cable causing slow spinning when it gets corrosion under the cover. Make sure the cross over cable doesn't have the same issue or it will kill the batteries with over charging.

 

[JBallou]

You can try unplugging the grid heaters 1 at a time to see if that isolates the problem.

 

[Prairie Dog]

A couple of years ago I bought two new batteries and one was shorted internally so you never know..
I would verify the batts are good by separating them and measuring their voltages.

Scott

 

[jandtjil]

Like Gas Man, I too am having similar starting issues. Am in the process of checking out relays and grids. If there were an issue with the ECM, would it throw a code?

JJ

 

[DonFitzwater]

Like Gas Man, I too am having similar starting issues. Am in the process of checking out relays and grids. If there were an issue with the ECM, would it throw a code?

JJ

Don't make this too complicated. Stick to the basics and rule out batteries, cables and grounds first. If you have a few miles, might be time to look at your starter. You can also perform a voltage drop test across the components to eliminate each.

 

[jandtjil]

DFitzwater thanks for the response
Yeah the batteries are going to be an issue here as both have been beat down a few times. But I am reluctant to replace them until I find the cause.
The grounds, well that may be adding to the problem, but I think having 44mv present at both heater relays (key off) is not a ground issue. Unless a ground to the ECM could cause it to allow the voltage when off??
Will go pull (and clean) battery cables, check grounds and PCM connections
I don't want to hijack Gas Mans thread I will be reposting in the 2nd gen/engine-trans area once I run some of this down

JJ

 

[p-Bar]

Pull one cable off 1 battery and see how it turns over then try the other one . Process of elimination