No start/no crank but starts with jump box

[Jason_Charowsky]

Hi all,

Chasing a new issue. Car will not start on its own with no cranking at all. But as soon as i put a jump box on it, it fires right up with no issue.

I have checked my starter and battery both at autozone and they both tested fine.
I am running out of ideas so any would be much appriated.

TIA

 

[ttocs]

start simple and check your grounds. By "check" I mean find them, inspect the wire, then remove the connection, clean both sides and then tighten it down two ugga duggas so that it will not wiggle even a little bit. Bonus points are awarded if you put a dab of grease over it or a splash of paint to prevent rusting.

 

[Jason_Charowsky]

Does anyone have a list of all of the grounds? Also is there anyway to test them with a multimeter instead of just inspecting them and hoping?

 

[ttocs]

just go to your battery and look at the negative terminal and follow the wires. One goes up to the core support and one down to the block. You can test for resistance with a meter and it should be low/close to 0.

 

[green5point0]

Are your battery terminals and connections clean and tight? If you can wiggle the connection at all then it likely will not carry the current that the starter draws.

 

[Jason_Charowsky]

They are all nice tight and clean, it is raining while im checking all this so sorry for the slow responses. The resistance between the negative cable and the two grounds on the rad support are better 0.7 and 0.8 between the neg cable and the ground between the driver side motor mount and frame rail is 1.2. How do i go about fixing this?

 

[ttocs]

yea that could be JUST high enough to cause problems. As I said before remove the ground connections and then clean the connections and once again measure the wires resistance and see if it is any lower. If it isn't ya might want to start by replacing them as it is not difficult or expensive job that will be done sooner or later.

 

[Jason_Charowsky]

Now I also have issues with my gauges reading higher or lower than they should be. I know they are dummy gauges but could this also be a result of the grounds. Also are there any other grounds I should check other then the three i mentioned?

 

[Terrorist 5.0]

I had a similar issue. I’m not sure what this wire grounds, as I just replaced it after looking at it and finding it unfit, but the ground strap that goes from the driver side exhaust manifold to the frame rail could be your culprit. I had similar symptoms in that my car wouldn’t start unless it was jumped.

Turns out, when I removed my inoperative A/C (probably the best thing I ever did in terms of making the car easier to work on, and in general), the stud that the ground cable is fastened to, was rusty. Difficult to clean, so I relocated it to the A/C compressor bracket, which was now open. I also cleaned the other end. I should also mention I bought a new cable, as the old one was burnt from occasionally touching the exhaust manifold. I must have not been careful enough the first time around when I removed it to get at a bolt while removing the A/C.

I’m all for doing things the right way, with a multimeter and properly checking resistances and all that fun, but your eyes will often times lead you to the problem much quicker than fancy tools will.

 

[ttocs]

I have to agree the meter might find something that you can't see if you really looked but most of the time you can find some corroded wire, rust that has developed between the connections, ect.

 

[duh09]

Quick, easy test for a bad ground- use a decent set of jumper cables from the negative post on the battery to a good ground. I usually do that and run the positive as a ground from the engine to the chassis somewhere as well.

 

[Jason_Charowsky]

Car starts and all my gauges read how they are susposed to now. Took the ground strap from that frame rail to the motor mount off and got it all cleaned up. It was rusted to all hell on the body side which makes sense to why it would not start. Resistance is now down to 0.6 and car dosent sound like it was breaking up like before.

 

[ttocs]

almost all the sensors in the motor use resistance to read their readings. The temp senders are thermistors that change resistance with heat, the TPS uses a variable resistor that changes resistance as you give it gas. The ecu reads these changes in resistance and the voltage across them to know what is going on so when you add .5-1.5 ohms of resistance to each of those senders the motor gets confused and does not add enough air/fuel/ect.

 

[Miltoid]

They are all nice tight and clean, it is raining while im checking all this so sorry for the slow responses. The resistance between the negative cable and the two grounds on the rad support are better 0.7 and 0.8 between the neg cable and the ground between the driver side motor mount and frame rail is 1.2. How do i go about fixing this?

You need to check the voltage drop across the neg and pos cables.