1998 V70 New onset non start. Ignition switch test?

marrymemercedes · Post by **marrymemercedes** » 23 Sep 2015, 23:09

Hello all,

First post. Great forum! My friend recently picked up a 1998 V70 FWD wagon with an automatic transmission. It is in great mechanical shape for the year with a few cosmetic issues and a couple of other common for this model issues. It’s exactly what he wanted and the car is great! As the resident shade tree mechanic in our circle of friends I have been tasked with rectifying it’s issues. However I’m not familiar with these cars as all of my experience rests in Mercedes 190e and 300e (W201 & W124). To my buddies credit he is helping me and keen to learn along the way.

Already replaced have been: the ABS/Tracs module, rear door opening mechanism, gas cap, driver side indicator housing and a few surface rust spots. The last remaining major issue is that the car no longer wants to turn over (ie. Everything on the car works but the car)

Symptoms are: It does not turn over (although it did previously). Battery is good. Starter relay is functional. Starter motor is good. The first time it didn’t start we were pushing the car back home and when we got to parking it my friend got violent with the transmission. Voila it turned over and started several times before failing again and not turning over. The ignition switch or tumbler is probably on its way out as it is a little finicky returning all the way back to the auxiliary position after being started causing the low beams/indicator lights to periodically not work (like the 105 relay is toast) however when manually eased back all the lights function as they should.

With a little reading the two biggest culprits would be the ignition switch at the tumbler and the PNP switch (I’m new to these cars so am open to other suggestions, my ego would not be bruised).

I would like to know what the best way to test these components are so that we aren’t throwing money at the problem willy nilly.

I apologise if this is a common question. I tried a quick search and couldn’t find the answer and I’m studying for an exam this Friday so exam stress has got the best of me

. Thanks in advance for all the help!

Post by **abscate** » 24 Sep 2015, 00:07

More likley to be the electrical part of the ignition switch which is covered by many threads in the VRD

Very common repair in old age.

Post by **BEJinFbk** » 24 Sep 2015, 08:20

There's not really a test procedure for the ignition switch.
The symptoms that you've described make it a likely candidate.
Add that it's a well well known point of failure, it's probably
worth replacing. About $50 should get you an OEM replacement.

marrymemercedes · Post by **marrymemercedes** » 24 Sep 2015, 09:28

Thanks for the rapid responses. Sounds like I'll be replacing the ignition switch this weekend. I will post soon after with the results. Thanks again!

Post by **BEJinFbk** » 24 Sep 2015, 14:12

20 minute job - Cake!

marrymemercedes · Post by **marrymemercedes** » 26 Sep 2015, 19:10

UPDATE

The ignition switch was replaced with an OEM piece and success, the car started... for a total of 5 times. When it did start immediately after the replacement it started without issues. The car drove well when running and ran for 40 minutes. An hour later the car wouldn't start and was exhibiting the identical symptoms. I'm not sure where to go from here. Is there something else in these cars that can fry ignition switches? faulty part? Something else?

Any advice or suggestions are greatly appreciated.

Edit: for what it is worth the car is completely stock, not even an aftermarket radio.

Post by **abscate** » 26 Sep 2015, 20:05

Test your alternator output to see if it's over-voltage.

Test the starter draw at the solenoid ..you might have to remove it and take it to an auto electrical shop to do this.

Post by **Ozark Lee** » 26 Sep 2015, 21:03

I'm leaning toward a PNP switch problem. Try rowing the shifter back and forth, quickly from low to park, a couple of dozen times and see what happens.

...Lee

marrymemercedes · Post by **marrymemercedes** » 26 Sep 2015, 22:16

Thanks for the rapid replies!

I will investigate the starter draw and the alternator output. Are these common issues causing ignition switch malfunctions or am I wading into unknown territory here?

Before replacing the ignition module I did give the shifter several dozen forceful rows from park to low with out success. The PNP switch was high on my initial problem differential but after it started a few times immediately after the ignition switch replacement it has moved further down my list. Is there a way to test the PNP switch?

Thanks again for all the help and suggestions.

Post by **BEJinFbk** » 26 Sep 2015, 22:28

abscate wrote:Test your alternator output to see if it's over-voltage.

Test the starter draw at the solenoid ..you might have to remove it and take it to an auto electrical shop to do this.

What's your battery voltage when it won't start?
Have you run any voltage drop tests from the alternator
to the battery? How's the B+ cable?