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Tom, ASE Certified Technician
Category: Volvo
Satisfied Customers: 25954
Experience:  ASE Certified Master Technician
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Volvo S70 GLT My car will not turn over after I have driven

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My car will not turn over after I have driven about 100 miles until it cools down again. To start my car, I have to flash my lights first and then try the ignition. It starts when cold. I believe my car, 1998 Volvo S70, may have had a simple anti-theft device installed but I can not find it to disable it to see if this might be the problem.
Have you had the battery tested a weak battery can cause this. Also it will only start with the lights on correct ?
Customer: replied 6 years ago.

Yes, the battery has been tested and maintains a full charge.


The Volvo operates with the lights set to always be on low beam. To start the car, I have to toggle the switch for the high beams. The high beams flash and I turn the key in the ignition. The car starts. But, after driving for 50 to 100 miles and with the engine warm, if I turn off the engine I can flash the high beams but the engine will not turnover.


Hope this helps!

Does it crank and not start ?
Customer: replied 6 years ago.

When the car is hot, I can pull back on the cruise control stalk to the left of the steering wheel to flash the high beams. The low beam lights are on. The information lights are all on. And, the engine will not crank. When the engine does crank, when the engine is either cold or not very warm due to a trip around town, the engine cranks and the engine starts. From there on the car operates great!

Ok sounds like and issue with the aftermarket alarm starter kill.You will most likely have to remove it to fix this issue is this something you want to try yourself it can be pretty involved.Sounds like the relay for the kill switch is not operating correctly or the brain .
Customer: replied 6 years ago.

If I could find the aftermarket alarm under the hood I would attempt to disable it, however, I have looked on the firewall and see nothing that looks like a switch, so, I expect I will need to have a mechanic look at it.


I have mentioned this to them before over the last 10 years and the answer is always the same, "Bring it back when it is creating the problem!" To do this I would have to drive a long way and because the problem is intermittent, I can arrive and the car will just start like there is no problem.


But, let's assume the aftermarket alarm starter kill is not the culprit. What would be the next possible cause of this, if anything?


Will the computer register any error codes that a mechanic may use to understand the problem?

The other common issue could be an overheated starter or stater relay or loose or corroded battery terminal .Look under dash drivers side and see if there is a little black wallet shaped box which would be the alarms brain . Disconnect the connectors. If the problems goes away that was the issue. If not you need to have those other items checked. These would be the next steps . Hoped this helped . Positive feedback and bonuses greatly appreciated .
Customer: replied 6 years ago.
I found a box right behind the front headlight and beside the battery. It is only held in there by a zip tie and is floating free; looks like the box.. Four wires go into the box. I can unplug the attachment for these four wires and see what happens. Should I expect the car to start?
Yes this will disconnect the brain . Just make sure key is out of the ignition when you remove it .
Customer: replied 6 years ago.
I unplugged the four wire connector and I could not get the car to crank with or without flashing the high beam. Plugged it back in and flashed high beams and the car cranked. So, I have located the box. Has no nomenclature. There are two black and two white wires entering the box. If I cut the wires removing the box should I connect the two white wires and then connect the two black wires completing the circuit?
Yes I would try that next . To bypass the unit.
Customer: replied 6 years ago.
Thank you for your follow-up. The black box that I found was not part of the anti-theft system; it controlled the lights for my trailer hitch according to my Volvo mechanic. Have not driven the Volvo far enougth to experience the problem recently. Volvo mechanic suspected the positive lead to the circuit box. I replaced it and am not sure if my problem has been resolved.
Ok if you need any further help let me know.
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