Neutral Safety and Automatic Shutdown swithch

20

Asked by Apr 30, 2017 at 08:26 AM about the Dodge RAM 150

Question type: Maintenance & Repair

1985 W100. Having trouble starting. Check wiring and new ECU, Voltage Reg., distributer, coil, start run relay, resistor. So pretty much all. Never been done since I bought it in 85.
Question 1: if the back up lights work is that proof the neutral safety switch is good. I read on one site it was.
2: Some of the manuals refer to the Auto Shut Down switch. I can't find it in the manuals I have but neither of them is specific to 85 alone and the 85 gets passed over a lot. One place said it was under the dash but my wiring diagrams for this vehicle don't show one.  
Any help would be great. Thank you.

31 Answers

74,625

There should be a separate switch to activate the back-up light. More than likely the problem lies with the ignition switch, and possibly the neutral safety switch.

2 of 2 people found this helpful.
20

From what I had read the neutral safety has 3 pins, the center was for the shut off and the others were the backup lights

74,625

I'd have to look on that, but I see a separate switch for the back-up lights. When I look up the neutral safety switch, it is as you describe and says nothing about it being part of the back-up light system. Not to say that it is not.

1 of 1 people found this helpful.
20

When I look at the part at O'Reillys auto parts it shows a switch with 3 pins and in my auto manual says it is mounted on the transmission. Part of my problem is my vehicle isn't listed in most manuals. The 1985 100 Custom or W100, from what I was told wasn't made in 1985 so I usually had to ask for 1986 parts.

74,625

So, did you get the switch to try? From what I have seen, the revers lights would work off of this switch also. This looks similar to a back up switch I had to look up on an other vehicle today, 3 prongs. But that is all it did, operate the back up lights on this truck. Your switch says it is a neutral safety switch. Check it out on this sight.... https://www.carid.com/mopar/neutral-safety-switch-mpn-w0133-1670065-mpr.html?singleid=8374215&url=58687241

1 of 1 people found this helpful.
74,625

The ignition switch is more likely to be the problem than the neutral safety switch.

1 of 1 people found this helpful.
20

I noticed while trying to start it with a timing light on it I only got a spark once on number one. I am still doing new cap and rotor making sure all wires are correct but hope to try again today. One manual said to try starting in neutral. I am leaning toward the ignition though. Thanks for the help!

74,625

I see your post did not go threw either, they must be having a problem, but I get your response in my e-mail. So give me a minute, you gave me some useful information.

74,625

What size is this engine?

74,625

I'm thinking to take the ignition control module out and have it tested. This distributes the spark.

Best Answer Mark helpful
20

I have just put a new one in again. Just haven't finished the new cap and rotor. Also reorganizing plug wires. Hoping it will work. Thanks

20

Missed your question, it is a 318 or in today speak 5.2

20

I bench tested both ECU's taken out. With 12 volts to pin 1 I only get .57 volts on pin 5 and .44 on pin 2 nothing on 4. I would imagine with the .57 there is something wrong with these two ECU's.

74,625

I don't know, i would need to see a wiring diagram. I don't know what the pins a for, voltages don't sound off the wall.

20

I was talking to a gentleman at NAPA and he was saying I should have a spark control computer under the dash. I can't find it. What brought that up was a guy, working on it wired both the red and blk w yellow to the positive side of the coil. ?? Well I have gone ahead and replaced the ignition control and new distributer. Don't know if he damaged the distributer though. The napa man said it may have damaged the spark control too. Getting harder by the day. Anyway I am in the process of putting it all together to see if it will start and check spark at coil and plugs and voltage everywhere. Then I will see whats next. I am attaching a copy of the wiring for ignition. Thanks for the help.

20

If it helps this truck was made 3/85 so being the w100 and not being found in auto parts stores hasn't helped. I was looking for the external resister that goes on the neg. side of the coil. (probably noise resister) but no one has that either.

74,625

That ballast resistor is for starting in making the engine run and is a common part for Dodge, it is either a 2 prong or a 4 prong resistor. When it is burnt out the engine will turn over but not start. Remembering back in the day in fixing starting problems on Dodge, repairing that wire to the resistor, eventually the wires get hot enough times that it looses continuity, and a new section of wire then was put in.

1 of 1 people found this helpful.
20

I know when I turn the key to on not starting the top of the resister is hot. I will have to check the plus side of the coil for juice. Mine is the two prong. I also have an EGR time delay on the wheel well that has leaked black stuff out but everyone tells me that doesn't matter. The manuals also talk about a lean burn system. Not sure how to tell the difference. With the spark control computer it seems some of them had it and some didn't. Odd setup. I did look under the dash on drivers side and didn't see anything but will do another check. A lot of questions but I will know more when I finish putting the coil back and starting it hopefully. Thank you for your advice. Hard to find anyone that knows much about old Dodge trucks.

20

I finally put the coil and all additional parts back in and started checking everything. The top of the Ballast Resister has 12 volts. The bottom has 7.2. When I checked the + side of the coil with the ignition switch on it had 6.5 volts and when we cranked it over the - coil side only had 1.5 volts. It sounded like it was going to start for a second. I tried adjusting the vacuum advance and that was when it almost hit. The voltage is bugging me. I ran a couple tests on the other ECU and when I put 12 volts to the # 1 pin the other pins only had partial volts and the 5 nothing. I still have the latest ESU on but don't know if there is a problem with that one and can't find anywhere that tells me what ohm or volt readings I should get on testing. I looked all under the dash and behind the battery etc. and there is no Spark control computer someone had mentioned at NAPA. He had an 88 and they have them. So this is where I am at this time. I even ran a hot wire to the + side of the coil and still had no luck. Suggestions would be great. Thanks

20

I also did some testing on the old ESU I had removed and had varying results from both. Not being able to find what the results should be if I put 12 volts to the #1 pin really leaves me in the dark.

74,625

Have you checked any Dodge forums?

20

I did and found mixed results. A few mention the spark control I don't have. When I tested the coil from + & - to the center I got 855 ohms. Nothing from + to - I got no reading at all. On one site it showed a reading on others there shouldn't be one. On two sites they said 85 dodge coil should read 10,000 to 11,000 ohms I only got between 850 and 950. Finding the correct numbers seems to be the challenge.

74,625

Take it to a auto parts store to have checked.

1 of 1 people found this helpful.
20

Is there some way to check the neutral safety? I have read of others having a problem with low voltage to the coil, with no cure noted. I have 12 volts to the top of the ballast resister and 6.5 at the bottom. If I unplug the ECU I get 12 top and bottom. Some said the ignition switch but I have lights and everything associated. I traded in my ECU and got a new one but 12 volts on #1 pin still only gives me .66 volts on #2 pin. The diagram I was given said it should be within 1 volt. I am wondering if the ECU I have is not the correct one.

74,625

If I remember right, there should be a voltage drop from the resistor as they had a problem with burning out coils. Have you ben able to find any voltage wiring diagrams for the ignition circuit?

74,625

Trying to remember, the resistor concept may have ben for protecting the points from burning out. I remember I was surprised when Dodge still kept the resistor once they went to electronic ignition when eliminated the point system. I'll have to look into this to see what I can find.

1 of 1 people found this helpful.
20

I am trying to attach a couple of diagrams of what I have found so far. It didn't make it the first time as a pdf so I have done two pages as a png.

20

I am attaching the diagram the local elec. shop said the volts should be at each post. Not been working too well but will give it another shot. This is from a 5 page trouble shooting section in an old manual he had. He's not a Dodge man and said the only two he knew of that worked on these years were very old and may not be around anymore.

20

Wanted to bring this forward. I unplugged the wire from the top of the resister, the run side. I turned the switch on and did a continuity test from the plug to ground and it buzzed or completed the circuit. Seems I either have a short in the wire or the ignition switch shorted. I will try running a hot lead to the top of the resister and see if it starts and if not I will check the bottom, run side, of the resister for a short next. Since the switch feeds them both it may be there also. Want to say thank you guys for the help. Any ideas creat other thoughts to explore.

74,625

You may be on to something if your finding problems with the wires.

1 of 1 people found this helpful.
20

I will go out in a few and run a hot wire to the top of the resister, turn the ignition switch on and check for any other shorts. Then if not found, still with the top factory resister wire off try starting it. If it starts then I will put a toggle in the cab for the resister until I can change the ignition switch. Hopefully it is the switch. When the new switch is being put in I will have to check for a short again at that point to make sure it isn't in the harness.

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