1992 500SEL starting issue
 

Sometimes I will go out to start my 500SEL and it won't turn over.
I get all my lights and battery is full charged. I have replaced the engine wiring harness and car runs good when it starts.
If I just keep trying, it will eventually start. Sometimes it will turn over it in two or three tries but other times it will be more like 20 tries. Also dash lights do not dim at all when i try it and it does not work. I heard somewhere that a few other people had a similar problem with different models. Was the K40 relay. Does this model have a K 40 relay?
Thanks. Jay

Presuming it's not the starter going bad, I would check all the fuses first, especially fuse #5. Check the ground terminals in the engine compartment behind the right front strut for corrosion. If you can get under the car, check the wire in the lower engine wiring harness that connects to the starter.

Also, the neutral safety switch has been known to cause intermittent starting. Have you pulled the codes to see what's there?

There is a K38 relay behind the instrument cluster that you will find in this post. http://www.peachparts.com/shopforum/tech-help/269799-how-disable-alarm-1993-w124.html

I thought they were a k38 relay,your car might,its next to the gas pedal under the carpet,on the transmission hump.when they go bad,the engine will not turn over.Sometimes holding the key at start posistion for 2 to 3 minutes they will start.on my car its behind the fuses under the hood

I have checked all the fuses and ground straps. I have not pulled the codes yet. Will try replacing the K 38 relay.
So is it behind cluster or next to gas pedal under the carpet? Thanks so much for the reply's

The K38 is the shiny ice cube relay behind the instrument cluster on the upper left side. You can see it in the picture at the link I posted. You can jumper that relay just to see if that's your problem.

If your neutral safety switch has not been replaced, I think that is a more likely candidate. You really should either buy or build the code reader and check the codes before you start throwing parts at it.

There is a kickdown switch under the gas pedal but I don't think that's causing your intermittent start problem.

When you say ``You really should either buy or build the code reader ``
What kind of reader is it and how can I build one
Thanks. Jay

This might also be a bad ignition switch issue. When the issue presents itself, try moving the steering wheel position adjustments both up and down and in and out. That will flex the cables to the switch. If the starter engages after moving the wheel position, the switch is bad.

Jay,

Scroll to the bottom of this page under Home Brew DTC Tool K6JRF Auto Page

Build the tester and then pull and clear the codes on each module. You will probably have quite a few if they haven't been cleared in a long time. Focus on the codes that come back after you've cleared them all.

I used three large paperclips for my tester where the terminal ends plug into the 38-pin cannon plug. The schematic shows these as banana plugs. This tester is not difficult to build. I am not an electronics guy and I built it in about an hour. I've used it hundreds of times over the years.

If you don't want to build it, I think they are available on ebay.