Volvo V70 2000, No start. Electronics Working

thomasanddaboys · Post by **thomasanddaboys** » 20 Oct 2021, 22:07

Hi there,

My Volvo wont start, all the electronics work when the key is turned to on. Radio works, windows go down, weirdly the power locks don't work. No response from the starter, just a low hum. Battery, Starter, Alternator all fine. Mechanic says it might be something to do with the Anti theft module. Did a bit of research and wonder if it could be the CEM or the Immobilizer also. Anybody ever encounter something like this?

Thanks

Post by **scot850** » 20 Oct 2021, 22:14

Have you tried to lock and unlock the drivers door lock manually with the key a couple of times? That will reset the immobiliser if that is the issue. I did once have to disconnect and then reconnect the battery one time to get the system to reset.

Next might be the park neutral switch. They fail in time. Try rowing the shifter back and forward several times as that can clean the unit to allow the car to start, or try to move the shifter to Neutral and see if it starts or turns over there.

Neil.

Post by **RickHaleParker** » 20 Oct 2021, 22:21

Hum from the starter usually means low current capacity. Check for / Clean corrosion on the battery cables and terminals. Both cables and both ends of each. You are looking for something that will cause a large resistance and produce a large voltage drop as the current goes up.

Windows ect, will not produce a large voltage drop because they draw 10s of amps. The starter draws 100s of amps. That is why the Battery cables need to clean and in good condition. 100s x a little bit = A lot.

thomasanddaboys · Post by **thomasanddaboys** » 20 Oct 2021, 22:41

Heading over to the mechanics after work tomorrow and will check for all of these things. Thank you very much!

Post by **FireFox31** » 20 Oct 2021, 22:46

When you turn the key to crank, do you hear a click? As I recall, that's either the starter or a relay to trigger the starter. If you have no crank and no click, then you may have bad grounding straps between the engine and the car body. There are two at the rear of the engine, one at each corner. They may look green from copper corrosion. The driver's side one attaches pretty high on the firewall, the passenger's side one attaches low and out of sight.

The attached picture is what you don't want to see, both straps broken. The failure may be more subtle. On my 2000 V70, the car started early one day and failed to start later that day. The straps looked fine, but were actually very brittle from being corroded.

Since I haven't gotten around to manufacturing grounding straps and offering them here, you can easily make your own. The second attached picture shows a heavy gauge wire bolted to any old engine point, running directly to the battery. This engine starts fine with this solution.

Post by **abscate** » 21 Oct 2021, 01:23

You can bypass everything in the cranking circuit (except the PnP switch in an automatic transmission ) by applying 12V directly to the white connector under the kidney fuse box under hood

Details are here:

location of starter relay bypass on P80