Starting Issues 2008 XC90

stljrdnfan · Post by **stljrdnfan** » 29 Nov 2017, 18:27

Ok, I'm at a loss. I have a 2008 Volvo XC90 that doesn't like to start. I've replaced the battery and the starter.

It sounds like it's got a low battery, it will slowly turn over and sometimes it will start and sometimes it won't. If I connect jumper cables to the battery the symptoms are the same, but if I connect jumper cables to the Positive terminal up in the Fuse Box it will fire up w/out an issue. Also, If it won't start at all I can connect jumper cables from it's current battery to the front and it will almost always start. It still cranks slow when I do this, but will at least start.

I figure it has to be an electrical issue at this point and was hoping someone could give me some points to check. There is 0 Ohm resistance from the battery positive terminal to the lug in the fuse box and 0 Ohm resistance from the Ground battery lug to the grounds in the engine compartment.

Post by **RickHaleParker** » 29 Nov 2017, 18:59

You need to measure the resistance in milliohms. 100 milliohms (0.10 ohms) would created a 5V drop at 50 Amps.
Do your test again but instead, measure the voltage drop from the battery to positive terminal up in the fuse box when cranking. The voltage drop when cranking will tell you more about the condition of the cables then an ohm reading. A lot of times, it just tarnished or corroded connections, try cleaning both sides of the connections with wire brushes or emery cloth.

stljrdnfan · Post by **stljrdnfan** » 29 Nov 2017, 19:16

Is that positive cable a straight shot from the battery? Wouldn't corroded connections cause the same symptoms when connected to another vehicle to jump start? Don't get me wrong, I will try your suggestions, just asking.

Post by **jimmy57** » 29 Nov 2017, 19:48

You can't reliably find large gauge cabling issues with any ohmmeter reading of any type. Two reasons: the error from leads and the stray currents from capacitors in so many of the modules. Whenever an ohmmeter is used in a circuit where there is not ZERO current flow then the meter will give a wrong reading. Maybe show 0 Ohms when there is resistance or show several ohms when nothing is wrong.
Use a volt meter and a long piece of wire or any gauge to connect to batt pos post at rear and then go between the extension wire and the pos stud in the fuesbox in engine compartment. Now crank over engine and watch the meter. If that is 0.2V or less then use meter between that post and the one on starter for the lead that comes form that post. Again , with starter spinning engine over see what voltmeter reads. 0.2V or less is great. You should open the fusebox an remove the fuel system relay. It is labeled as such. The starter will run for 5 seconds or until you turn and release key again if you want to stop it before 5 second time out.
You might get a 13mm deep socket and tighten the nut on the post in back of underhood fuse box where the battery cable junctions to that fuse box and to the starter cable and see if that is all it is.

Post by **RickHaleParker** » 30 Nov 2017, 02:10

Is that positive cable a straight shot from the battery?

Electrically it is a straight shot. Electrical/Mechanical it is not a straight shot. There are mechanical connections along the way, these are what you need to check. When I say both side of the connector, I mean the two surfaces that come in physical contact with each other. Shine them surfaces up. The connection that most often causes these symptoms if the connection between the battery post and the battery cable. I would start there and work my way to the fuse box, testing after each connector is cleaned up.

Wouldn't corroded connections cause the same symptoms when connected to another vehicle to jump start?

If you connect the jumper cables to the battery it would. If you connect the jumper cables pass the problem it would not. Exactly what your own test results produced. Based on what you wrote, your problem is between the positive battery post and the fuse box.

stljrdnfan · Post by **stljrdnfan** » 30 Nov 2017, 14:15

Cleaned both battery posts and cables, and the positive leads up at the fuse box with no change.

Haven't had a chance to check Voltage yet, will get that a little later this evening

stljrdnfan · Post by **stljrdnfan** » 30 Nov 2017, 16:27

Ok, have some new info.

Testing Volts from pos terminal on battery to stud on fuse box, stayed mV

Volts from pos battery terminal to ground dropped down to 7.4 when cranking
Volts from Stud on fuse box to ground dropped to 6.0 when cranking

Also, this battery is 730CCA, is that a big enough battery for this vehicle? I read somewhere that I should have at least 800, would that cause this symptom?

Post by **RickHaleParker** » 01 Dec 2017, 03:18

Pull both the positive and negative cables off the battery and use a tool like the one in link the one below or some emery cloth to clean the battery terminals and the insides of the battery terminal clamps. If that fixes it fixes the problem, ignore the rest of this message

One note on the tool, there is a second brush under the cap for the battery clamps.

https://www.walmart.com/ip/Everstart-98 ... 3=&veh=sem

Else:

Your numbers are not adding up as I would expect. Take six more measurements. Hook the voltmeter across the battery ... not the battery cables at the battery, put the voltmeter probes directly on the battery terminals, record the voltage not cranking and cranking.

Next do the same with the voltmeter probes on battery cables at the battery, record the voltage not cranking and cranking.

Then move the positive lead of the voltmeter to the jump start stud near the fuse box, record the voltage not cranking and cranking.

Post the six measurements here.

I'm almost ... almost certain the problem is the positive battery cable between the battery and the jump start stud ( assuming you did use the tool or emery cloth as instructed above) .

One more thing, the starting circuit on the 5 cylinder is different. Do you have the 5, 6 or 8 cylinder engine?

stljrdnfan · Post by **stljrdnfan** » 01 Dec 2017, 07:58

I did clean the battery studs and inside of battery cables from your origional post. When I get the reading on the jump start post, should i just put the negative to ground? Or keep it on the battery negative?

Also, I have the V8 engine (I'm not very car savy, but want to try everything before I take it to a dealership)

I've already removed the rear and 3rd row seats, is there a point where that positive cable would typically fail?

Will get those readings for you as soon as possible

stljrdnfan · Post by **stljrdnfan** » 01 Dec 2017, 09:10

Ok, so here are the readings I got

Battery Posts - 12.34 - 9.0-9.9 cranking
Battery Cables - 12.34 - 9.0-9.9 cranking
Jumping Post (Put negative to ground) - 12.34-6.9-7.6 cranking