1960StudebakerHawk... My background is electrical so I was naturally drawn to the schematic and particularly the portion I pasted because it represents the entire function (lack of function) from "The Key" to the "Starter Motor" and mostly everything in between. Obviously the branches at 27 n 35 are not shown. You pointed them out somewhere above. I took a look and jumped on because I felt the OD switch was trying to reveal something.

Just after I replied I was reading more of what you wrote and realized I missed your comment about it, (OD) switch, NO LONGER behaves the same. With that in mind it might not reveal as much as when it was consistent. That's why I threw in the link to checking starter for good grounds etc...

Appreciate the opportunity to learn. Keep us posted and good luck!
JC

 

JC.....Thanks for the follow-up reply. Great to have you and your electrical background to ponder this situation. Regarding the schematic, I was studying it more yesterday and realized that the branch at "35" (2B-L) where the electrical flow branches off and also provides power to the "Tranny, Fuel Injection, and SRS" does in no way cause any interruption in current going to the starter solenoid. I had initially thought that some malfunction in those items after the "35" branch could impact the ability of the solenoid/starter to work. Those items at the "35" branch merely are fed power from the circuit, but have no "veto" power to the current going down to the solenoid/starter. Do you agree with this? Or, could a serious issue in those areas (Tranny, Fuel Injection, and SRS) perhaps cause such an amp draw that it would severely reduce the amps flowing down to the starter solenoid? The reason I ask is because yesterday I crawled under with my voltmeter, and connected the positive lead to the "Trigger Wire" (which is the wire 2B-L shown in the schematic above and below the "35" branch), and the negative lead to ground. I had someone turn the ignition key to "start" as I read the voltmeter. I did this several times, and only got about .15 volts at the end of the Trigger Wire. This would be way too weak to allow the solenoid to engage and allow the starter to crank. Shouldn't I be getting about the same voltage at the Trigger Wire as the voltage at the battery....12.6 Volts?

I also did a simple "screw driver" test......I used the screwdriver to make a connection between the Battery Cable connection at the solenoid and the Trigger Wire connection at the solenoid.....and it performed as it should, created a good spark and the solenoid engaged the starter.

Let me toss in another oddity to dwell upon: A nearby friend owns a 1999 Montero which is pretty much the same rig as my 94. He has also been having this persistent "No Crank" issue for the past 6 months. He typically has to turn the key to the "start" position about 5 times before the engine cranks up. He had thought it was the ignition key switch after replacing the starter, cables, etc......so he even replaced the ignition key switch on the steering column, and he said this did not help. A few days ago (after I had discovered that the OverDrive switch seemed to have an impact on the ability of it to start), I suggested that the next time he turns the key and has a "No crank" problem, to reach over and turn off the Overdrive switch. He then told me that he did this, and it started right up. However, turning the Overdrive switch "on" or "off" could just be pure coincidence in helping the engine crank. Maybe just one of those psychological things where we "think" turning the OD switch "off" will allow it to start, and our mind is just sending out positive vibs which allows the engine to crank.......Who knows for sure.

But I would like to hear what you say about the volts being only .15 at the Trigger Wire......Not 11.5, Not 1.5......but a super low reading of .15 Volts when the key is in the "start" position.

I have already ordered a "Ford style" starter solenoid and a 30 amp push button switch. I plan to just mount a push button switch in the dash and run it to the Ford solenoid on the inner fender about 2 feet from the starter, and wire this new trip wire to the existing trip wire. This way if the ignition key switch fails to work, I can reach over and push the back-up starter button. This will end all the frustration I have been having on this bizarre issue. What say you?

 

Getting the voltage reading from the "Trigger Wire" while turning the starter key:










This time there was not enough voltage to light up the test light. In a prior test at the trigger wire, I did have a bright light on the test light. .15 Volts......shoot, a worm would have a higher reading on a cold day in January when molasses does not flow. Captain Kirk would say, "Scotty, we need more power! Gotta have more power NOW!"

 

I agree that under normal conditions the other legs @ 35 shouldn't have any affect. Without seeing that part of the diagram my "guesstimate" is it's purpose is to either supply power to the legs and/or to signal that the key is "now" in the start position and the logic on the other end should adjust/react as designed.
That being said there should be ~12V @ the [Trigger] connector you removed in the new pic. (Meter pos at connector neg to a good gnd.) Hmm... where does the red cable you inserted into the connector go?

The screwdriver working, suggests that the IGN Start 12V isn't there to energize the solenoid. Suggesting the problem is somewhere up stream. (2B-L) A jumper wire anywhere from the ignition switch start pin down to the A-04 would help to isolate. I'm guessing 2B-L is not easily accessed but it looks like right area to search where the 12V is getting lost or pulled down.

Note: If you opt to use the solenoids pin 1 (A-04) to attach the momentary switch you could use a much smaller one rated for far less current/amps. It only needs to carry the same amount of current/amp that the wire you disconnected at A-04 is rated for. The gauge of the wire will indicate its max current/amp rating. So match the push button's rating to the rating of the trigger wire.

Looks like you got a tricky one.
JC

 

StudebakerHawk, I'm glad to hear that jumping solenoid does engage the starter. Added to that the 0.15v on solenoid with key in Start position narrows the issue down to a wiring problem (wire break somewhere) or ignition switch now working in start position.
I would run another test: ignition in RUN position, jump starter solenoid eith a wire. Does the engine start? If so, that means all other systems work properly.
You could pull ignition swithch and probe resistance on the terminals. It is very possible to have enough cortosion to create excessive resistance in starter circuit or have a broken contact there. To check if it is wiring vs ignition switch, try jumping solenoid wires at the ignituin switch.
The OD button role is still puzzling. I have no explanation for that, except perhaps with a failing starter circuit, electricity flowed through some other circuit in which OD switch is located. That worked untill that circuit blew a transistor or burned out OD switch? Like I said - i got no basis for this, just spitballing. You know your truck best to see if any of this makes sence.

 

JC: Good comment. I would bet that the point of the "35" leg going to those other 3 items is to send an "alert" that the starter is engaging, and probably to temporarily turn off the power to those systems while cranking. I would not think that that little black wire with a blue stripe (the solenoid/starter trigger wire) would be the power feed for those systems......so probably just goes to relays which stop the primary current flow during cranking. Just my additional guess.

Red cable that was inserted into the "Trigger Wire" connector extends about 4 feet and then connects to the test light wire which you see in the picture.

The 2B-L (stands for black wire with blue stripe) is very hard to access. It goes into the main wiring harness and then goes up and on top of the transmission, and down the other side. It was a challenge just removing the Park/Neutral Safety switch from the main 12 pin connector.....I had to first remove the switch, and the fish it up over the tranny, and off a small hook, and that gave me barely enough room to pry the 12 pin connector loose and remove the switch and its wiring.

Yes, I plan to install the Ford-type solenoid on the passenger fender and then the wire going to the Solenoid "trigger" connection can be light gauge (same as what is there now would be fine). My plan is to leave the existing Trigger Wire, and just add the new one beside it.......so if I turn the ignition key, and she starts-up, fine. If not, I can use the push button starter. I dont think having two Trigger Wires hooked to the solenoid would be an issue, right?

Hunter: I just conducted your experiment......I turned the key switch to the engine "On/Run" position, crawled under, and used a screwdriver to touch the battery terminal end on solenoid to the Trigger Wire stud on Solenoid.......in half a second, the engine cranked, started, and was idling fine. I scurried out from under the rig, and climbed into the drivers seat, revved the engine a wee-bit, then turned the key "Off". I immediately tried starting again, and got the typical "nothing"......"No Crank/No Start".

Good idea.....I could pull the ignition switch and do the test you described. However, the fact that my friend's 99 Monty is doing the same thing, and he replaced the ignition switch and it did not solve the problem, makes me think that the issue is not in the ignition switch (maybe that opinion is easier to form knowing that I have a Ford-type relay and 30 amp push button starter switch on order). With his 99 Monty, he claims that during those times when it will not crank/start, that typically it will finally start after about 5 tries.

A common issue with both of these Monties might shed some light as to the issue.......His 99 Monty had a severe oil leak, and the prior owner had even constructed a metal shield to cover the alternator from getting ruined from the huge amount of oil leaking onto it. His engine/tranny and surrounding area was soaked in oil. This 94 Monty that I just restored also had a massive amount of oil leaking (bad head gasket with both water and oil leaks), and so everything was covered in oil.....and even the wiring harness connecting the Park/Neutral safety switch, and all the wiring was soaked pretty good with engine oil. So, maybe it is just simply voltage loss through oil that has soaked into the connectors?

OD Switch.......it will be interesting to see if it still works after I have rigged up the Push-Button Starter. Since the dash light "OD Off" still comes on, I believe the switch will still work. Maybe it triggered "just enough" back current or did something wacky with those electrons to "jossle" the starting circuit to flow just enough electrons to trigger the solenoid/starter???

 

The fact that the engine starts with the starter bypass, indicates that the issue of no crank no start is confined strictly to the trigger wire circuit on the starter. Where exactly is a mystery, but as you said - sounds like a common occurrence on that model of Montero. With that said, your idea of adding a backup start button with a different power pass to starter solenoid is a good one under these circumstances. I'm not sure what Ford style solenoid is, but I think you can get away with a simple relay. I would install a relay that is activated via a button on a dashboard. When activated, the relay should close the contacts between starter +12v post and solenoid trigger wire post. Think of it as the relay will acting just as the jumper wire you used to do the test. This way you can do all this with pretty light wires and you avoid adding any heavy gauge wires to the system which are needed if you're adding extra solenoid to run a starter

 

Hunter: Here is a picture of a "Ford Type solenoid", often mounted on the fender of old Mustangs and many old Fords. I suppose it is "overkill" for the job, and a simple little box-type relay would do the trick as you said.






There are also a couple connectors hanging near the starter that are oil soaked, and easy to get to to clean......I will give that a try, but not sure if those wires are even related to the starting circuit. I had wiped them off a bit already, but it would not hurt to disconnect them and give them a good degreasing: You can see the starter and its black/blue "Trigger" wire to the left.

 

Yep, I see it now. it's basically an external solenoid to provide a butt load of amps to the starter. I truly don't think this is the right way to go. This is dedigned to put through a lot of amps, hense the big fat posts for battery connectors. You don't need that. You have good 12v supply from battery to the starter and all you need is to divert some of that juice onto the trigger post of the starter to engage it. I would definitely just wire it trough the relay. Simpler and cleaner wiring too. All you have to do is to provide power to trigger post on starter. Based on the size of the trigger wire, there is not alot of amps flowing through that circuit.

 

Well, I got those oil-soaked connections degreased......but turns out the larger 4 wire one was a "dead-end"......I guess it was for antilock brakes which this rig does not have. However, has anyone ever done an analysis as to the actual affect that oil has on electrical connections? Im curious as to how much voltage drain or "prong to prong" volts can be transferred under conditions of severe oil penetration into these connectors......do electrons flow as good through oil as they do through water, for example?










Ford Type Solenoid: Well, one benefit of having that mounted under the hood is that you can easily use a screwdriver or wire to engage the starter motor, or to bump the starter to get the distributor at a TDC, etc. Will decide how to go once I start the process of installing the push button starter.