Wont start

Yes, transmission in that car has a neutral safety switch, if the car is not completely in park, it will not turn over, try to start it in neutral. If that works you may need a minor adjustment on the shifter or possible the switch replaced. These are an important safety item and should never be by-passed

Read the guide below,it will help

https://www.2carpros.com/articles/starter-not-working-repair

BATTERY/STARTING/CHARGING SYSTEM TESTING/DIAGNOSIS -1982 Mercede.
BATTERY/STARTING/CHARGING SYSTEM TESTING/DIAGNOSIS
TECHNICAL SERVICE BULLETIN
Reference Number(s): 15/1, Â Date of Issue: Â September 1983 Related Ref Number(s): 15/1
ARTICLE BEGINNING
HIGH NUMBER OF UNNECESSARILY REPLACED ALTERNATORS & VOLTAGE REGULATORS
Model(s): All Mercedes Benz Models
Group: Electrical
Bulletin No: 15/1
Date: September 1983
SERVICE INFORMATION
Recent inspections have shown that a high number of alternators and voltage regulators are being replaced unnecessarily. In all such cases, additional components, i.E. Battery, starter, ignition switch or neutral safety switch, are also replaced.
The importance of proper testing and diagnosis of the battery, starting, and charging system cannot be over-emphasized.
To avoid unnecessary replacement of electrical system components, be sure that all technicians are familiar with the following procedures:
1. Battery hydrometer test 2. Battery charging 3. Battery performance test 4. Battery drain tests a. Key "off" drain test b. Key "on" drain test 5. Starting system current draw test 6. Key switch/solenoid circuit test 7. Starter "hot" circuit test 8. Starter "ground" circuit test 9. Charging system tests a. Maximum output test b. Diode/stator test c. Voltage regulator test

WIRING CONTINUITY TESTDisconnect terminal plug from rear of alternator and connect a voltmeter negative terminal to ground. Turn ignition "ON", connect positive lead to each of the connector wires in turn. Voltmeter should read battery voltage as each positive connection is made. If not, trace each wire to find fault. VOLTAGE DROP TEST - GROUND SIDEConnect voltmeter between negative terminal of battery and alternator housing. Start engine and run at approximately 3000 RPM. If voltmeter reading exceeds.25 volt, a high resistance in negative side of charging circuit is indicated. If so, check for loose, dirty or corroded connections. OUTPUT TESTDisconnect terminal plug from rear of alternator and connect ammeter in series between alternator center terminal and corresponding socket in terminal plug. Connect a jumper lead between the "D+" terminal and its corresponding socket in terminal plug. Start engine and run at approximately 3000 RPM. Turn on headlights and leave on for 5 minutes. Ammeter should read maximum alternator amperage at normal operating temperature. REGULATOR CONTROL VOLTAGE TESTAll applicable regulators are designed to maintain from 13.7 to 14.5 volts at a load current of 5 to 7 amps. Alternator should be driven at 4000 RPM and load current set at load current rating. Resistance and speed of alternator may be readjusted if necessary. Read voltage within 1 minute. If not within specifications, regulator requires replacement. NOTE:Test cables should not be removed or load excessively reduced during testing procedure. Considerable load variations may damage the diodes.

Everything you described can be caused by a failing generator that is not fully charging the battery. As system voltage drops, more and more computers become confused and start to shut down or do weird things. The charging system is the first thing we check when you list a multitude of electrical problems. Have the system tested by your mechanic, not at an auto parts store. Post the results, and I will interpret the numbers for you.

A three-cylinder water pump with one dead cylinder can still fill a municipal water tower. A generator with one bad diode of the six will only be able to develop a maximum of exactly one third of that generator's rated output current. The standard generator for your car is a 55 amp unit which is very small by current standards, and was not much back in 1984, but it was sufficient when cars did not have a lot of unnecessary electronics. If your generator has a bad diode, the most you will be able to get from it during a full-load output current test is 15 to 20 amps. If the electrical system needs more than that, the battery will have to make up the difference until it slowly runs down over days or weeks.

All AC generators put out three-phase output current which provides a very stable and smooth voltage. The voltage regulator maintains that voltage between 13.75 and 14.75 volts. That is just the right amount to force electrons into the lead in the battery's plates, so they can be stored there. Just like you would get little pulses of varying water pressure from the three-cylinder water pump, you get little pulses of voltage variation from the generator. That is "ripple voltage". That cannot be measured directly. It can only be measured with a professional load tester found in repair shops. The testers found at some auto parts stores do not test for ripple voltage. That is why I send everyone to their mechanic for this test.

When a diode has failed, (those are one-way valves for electrical current flow), you lose one phase of output current, and during the time that missing phase is supposed to be there, output voltage drops a lot. That larger difference between the highs and lows is that high ripple voltage. My tester is sitting in the back of my minivan right now. I just performed this test on a friend's minivan, with the same results. The most we could get from the 90-amp generator was 28 amps, and ripple voltage was off the chart. Charging voltage was perfect at 14.4 volts, but the battery had to be charged with a portable charger about every other week.

The voltage regulator monitors system voltage, and most of them respond instantly to the low end of the ripple voltage by bumping up the target charging voltage. The regulator does not know when a diode has failed. It just assumes you're running a lot of electrical loads, and it needs to bump up the voltage to produce more current to meet the demand. The problem is when the next two working phases show up, output current is momentarily normal, plus the regulator is running the generator harder. It takes longer for it to decide to bring the target voltage back down. Before it does that, the next missing phase is detected, and the regulator continues to bump up the desired voltage. That is what you are seeing with the 14.75 volts.

This was one of my prepared "bugged" cars I built for my students to diagnose. The first time they saw the "battery" warning light on the dash, they became confused because charging voltage appeared to be fine. At the end of the learning experience they saw that charging voltage actually went up about 0.4 volts when the defect was switched in, and had they checked initially, they would have found full-load output current dropped from 65 amps to around 20 amps. Everything on the car worked fine, except for the "battery" light being on, because that car had very few electrical toys.

GM owners have a real lot of diode trouble with their 1987 and newer generators, and there are special considerations for those cars. For the rest of us, a diode can fail in any brand of generator, and while it isn't very common, that is the first thing we test for when we run into the symptoms you described. There is no value in searching for an elusive cause to a problem when a simple solution could be right in front of us.

Thank you. The only observation that could be not related is needing the engine to cool down before it would restart. The is a real comment complaint on newer cars and is usually caused by the crankshaft position sensor or the camshaft position sensor failing by becoming heat-sensitive. The engine cranks just fine, but there is no spark and no fuel injector pulses until those sensors cool down for about an hour. Those are on gas engines. Natural air flow over the engine while driving keeps the sensors cool. It is when a hot engine is stopped briefly, as in when stopping for gas, that the heat from the engine migrates up to the sensors and can cause them to fail temporarily.

Given the multitude of additional, related symptoms you are experiencing, you could also have a failure to restart due to a run-down battery. A hot engine is harder to crank, so the starter motor has to work harder, and that means it will draw more current from the battery. If the battery is run down to the point it can't supply that current, the engine will crank too slowly to start. Once the engine cools down, it will spin more freely, so it spins faster, and the starter needs less current to do that, so it is easier for the battery to supply sufficient current. The bottom line is a mostly-discharged battery that cannot crank a hot engine might be able to crank that engine when it has cooled down.

If this is all related to a charging problem, charge the battery with a portable charger, at a slow rate, for a couple of hours. If the charging system is the cause of the trouble, the engine will crank normally after charging the battery. Remember too that your engine uses glow plugs for starting, and those draw a real lot of current. Those can kill a discharged battery, so even if the starter is able to crank the engine yet, the air in the cylinders may not be hot enough to support firing the fuel.