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The manual states to do a back probe test on the synchro. No instructions for how to do this with the engine out of the vehicle.
There are 3 pins on the synchro connection. One is +, the other -, and the center one is stamped with a "0".
To back probe this "0" connector pin, all I should have to do is supply 12v DC battery power to the "+" connector, then ground the block to the negative battery terminal, then probe the "0" connector with my multimeter by turning the synchro until I get a "0" volts reading, then turn clockwise until the point where volts begin to show...then lock down the synchro retaining bolt.
Any argument with my plan to do this next step as described above?
Here are snapshots of the Haynes Manual procedure for the last step (back probe) to complete synchro installation.
I just want to make sure my "engine out" plan to complete this last step is kosher.
So if I do what is described in paragraph 17 through 19 of the synchro install instructions (back probe test) all I should have to do is supply 12 volts to the + pin on there back of the synchro, ground the - pin and put my multimeter probe on the center "0" connector and rotate the synchro clockwise until the volts read 0, then rotate the synchro slowly counterclockwise and stop exactly when the volt meter reading changes from 0 volts to a positive voltage reading. Then lock down the retaining bolt.
Hopefully you guys get what I'm saying.
Thanks again so much for your time. I really do appreciate this so much.
Hmmm I have never done this, I do not think it is needed. This is the part of the manual where you are getting way too involved just for a simple Cam synchro install. You see the synchro is driven off the camshaft and when you drop the synchro body into the engine block it can only mesh with the present gear on the cam (the one that is positioned to mesh with synchro at TDC)
As stated above if it was installed off a tooth you would be so far over it would hit the engine, or the vane alignment with the short mark would be WAY off......
The back probe instructions are to verify you have it set correctly, to me it looks like you are spot on = I would proceed
It says to disco the - batt cable LOL
It says bring block rotate the engine twice, back to tdc cyl #1 compression
Then advance it 26 degrees and start the back probe
Then hook up the battery and turn the truck on....to power the CMP
I do NOT think this sensor runs on 12V? I would not apply 12V direct without confirming the CMP works on 12V. It maybe a 5v reference voltage feed from the PCM...
There is a solid red wire for + supply, a smaller black wire with white stripe for - ground & a dark blue with orange stripe wire on the center "0" pin (as described in paragraph 17) as the wire to probe.
Couldn't I just measure ohms from the + pin to the "0" center pin and achieve the same result without risking damage to the CMP sensor by supplying incorrect volts?
Ohms would measure resistance in the same way the back probe test would measure volts?
I do understand what you say about the cam gear teeth being in matched to the synchro gear teeth for proper installation (which is where I am), but this final "back probe" step appears necessary to time the CMP to the synchro shaft. Just my thoughts. This would be the about the same as advancing or retarding a distributor cap to the rotor bug on a distributor shaft after correctly setting one in a block.
If it is a red wire, then yes that is a 12V feed
Yes you can use ohms
I understand exactly what you are saying and it is good to do things by the book
In the other thread I posted close to the top of this one, the exact same thing was discussed
The cam synchro for your 95 engine can be hard to get your hands on a new one, so many people over the years have successfully installed a later model CMP (3 wires same as yours)
The backprobing method ensures the correct timing signal is being sent to the PCM
The later model CMP uses a tool to align the flag to the housing body to ensure proper timing.
I was under the impression that I had to swap all my 95 sensors over to this replacement 96 motor due to the EEC IV system being OBD1 DTC on the 95 PCM.
In 96 it went to EEC V with OBDII DTC.
So I stripped all my sensors from the 96 engine and replaced them with ell the sensors on the 95, keeping that 95 harness.
I had assumed the synchro had to be swapped too because the two were distinctly different. Tell CMP Sensor was not interchangeable.
If the 96 synchro/CMP would have been useable on the 95 system, then why was I advised to swap?
The two CMP wire connectors are slightly different between 95 & 96 and I had originally posed this question at the top of the thread.
Geez if I could have left that 96 synchro in the engine that would have been great.
It's cool though, I learned something for sure. Learned a lot actually
turns out as long as you stick a 4.0L and 3 wire you can use the later years also, some have had luck with the 97 model year in the 94 and 95
I did not know this until researching the backprobe yesterday on your behalf for this thread....
We all learn that is why we come here and discuss...
I have never had luck miss matching years on the 4.0 cam synchro
There are at least 4 different synchroniers that fit in the 4.0L OHV
I always run into problems with the depth of the cam sensor, like trying to fit a 97 sensor into a 96 and so on. did not work for me..the 3 wire sensor was used from 94-97 and the 2 wire was from 98-01
The engine was from Ford from 1989-2000 model year
The upper and lower intake also changes
If you wanted to use all of that 96 stuff the best way is to completely convert your 95 to use the 96 PCM and wire up the OBD 2 system. You would have many changes to make to the power distribution and under hood wiring (so if you had the whole 96 as a donor then its easier)
At the end of the day you would have a 96 OHV
the 95 is bombproof and you did not have the 96 pcm, so.......
The safe bet is to ALWAYS park the two engines next to each other, strip both engines down to the block and heads
Then convert the new engine to match what came out.
Otherwise you can cause alot of headaches for yourself trying to get the instrument cluster, transmission, fuel, and ignitions system wired to work with the 96 stuff.
Like we said 95 is an odd ball year, some things are similar to 94, some are similar to 96
I am totally cool with making the replacement 96 block into a 95.
I needed to know how to do this synchro install anyway, as I plan to rebuild the old 95 motor completely and get another 95 roller like I have now to build from the ground up with lift for strictly off road.
I also want to do the 5.0L Boss 302 swap in my 97 Ranger.
Maybe next year.
Anyway bless you for the help. I am in awe of the knowledge I now have.
Now I'm off to attack this back probe test with ohms on my meter and see if it works. I will post updates.
Once I have the engine installed and started up, I will perform the volt test again by the book and see if it has the same result as using ohms.
Should be the same I would think.
Anyway much thanks!
Backprobing the CMP Sensor with engine out of vehicle (using Ohms) is unsuccessful.
I have had success doing the following steps (I got creative and this worked)
ENGINE-OUT PROCEDURE STEPS FOR CMP SENSOR BACK PROBE TEST ON 1995 4.0L OHV:
1. First set the #1 Piston to TDC on Compression Stroke. The needle on the Crankshaft Pulley (Harmonic Balancer) points directly at 0 degree mark. Then loosen the synchronizer retaining bolt until the synchro body rotates easily.
2. Find the 26° mark ATDC (After Top Dead Center) on the Crankshaft Pulley. (No such mark was present on my pulley so I made a mark myself with a chisel & hammer with a light tap.
I first made the mark incorrectly then corrected after checking with tape measure. The mark should be 1 & 11/32" ATDC from the 0° mark (counterclockwise if facing the pulley.)
3. Using a torque wrench or breaker bar & 19mm Deep socket, turn the harmonic balancer clockwise two revolutions to take up any slack in the timing chain, stopping at the 0° mark.
4. Continue slowly turning the pulley clockwise until the pointer is on the 26° ATDC mark then stop.
5. Note where the voltage indicator marks are for the 3 pins on the rear of the camshaft position sensor mounted on top of the synchronizer. One on the right is positive"+" middle is "0" and the left pin is negative "-" See image.
5. Using an AC to 12V DC Power transformer or a 12V DC Battery, (I used a 2 Amp 12V power supply for a WiFi router) connect the 12V Positive wire of the lead to the "+" pin on the CMP Sensor. Then connect the negative lead to the "-" pin. Then plug it in the wall or extension cord. Here is an image of the 2 Amp 12V DC power transformer I used for this test:
Here is an image of the power supply leads connected to the CMP Pins using alligator clips: (Make sure you have the 12V positive wire clipped onto the + pin on the CMP.
6. Set your volt meter to DC Volts to perform this test. Connect the negative probe to the negative aligator clip as shown in the image below.
7. Place the red or positive lead of the volt meter on the center CMP Sensor pin marked "0". See image:
8. Being careful not to touch the leads together, slowly rotate the synchro body counter clockwise until voltage appears on the meter.
Then rotate the synchro body clockwise until voltage reads 0. (No volts)
Then very slowly rotate the synchro body counterclockwise until the exact point when volts begin to show on the meter screen (my reading was 11.49 volts).
Lock down the synchro retaining bolt and disconnect the wire leads. You are done!
This is an image of the synchro vane position in the sight glass after completing this step:
Here is the position of the Installed Synchro in relation to the center engine line after completing this test: The Crank Pulley is still set to 26° ATDC in these last 2 images
I hope these instructions are helpful to someone else.