Renix CPS ? No spark

[Ecomike]

So what happens in reverse if solenoid #1 does not engage? Why does solenoid number 1 engage in R, if it is strictly hydraulic in R?

 

[kastein]

Solenoid 1 engages in R? That's odd.

I seem to recall testing this at one point; I am not certain if I did but if I did, the outcome was that solenoid settings have no effect when the shifter is in reverse. I don't have the valve body flow diagrams in front of me but if you have a copy of the FSM that includes the AW4 section, you can check if the solenoid positions will change anything.

 

[87manche]

I would not suspect NSS for a "delay" in gear engaement. Only if gear selection was intermittent, as in you select a gear, and the TCU doesn't respond unless you wiggle the shifter or move it in some way.

NSS it easy enough to test with a multimeter, but I don't think it's related.
Pressure test will tell you a lot, and it's also possible that the TV cable adjustment you made is the culprit.

 

[87manche]

The No. 3 valve body solenoid operates in reverse. When No.
3
valve body solenoid is de-energized, solenoid plunger moves away from
seat. This opens the drain port and releases line pressure. When No.
3
valve body solenoid is energized, the plunger closes the drain port.



NOTE:
For valve body solenoid usage, see VALVE BODY SOLENOID
APPLICATION table.


VALVE BODY SOLENOID APPLICATION (1)




Shift Lever No. 1 No.
2
Position Solenoid Solenoid


"D" (Drive)
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON
3rd Gear .................. OFF .................... ON
4th Gear .................. OFF ................... OFF


"3"
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON
3rd Gear .................. OFF .................... ON


"1-2"
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON


"R" (Reverse) .............. ON .................... OFF


"N" Or "P" ................. ON .................... OFF


(1) - Valve body contains 3 valve body solenoids. See
Fig. 2. No. 1 and 2 valve body solenoids are used
for controlling transmission shifts. No. 3 valve
body solenoid is used for torque converter
lock-up only.

Straight from the service manual

1988 Jeep Cherokee AUTOMATIC TRANSMISSIONS Aisin Warner 4 Electronic Diagnosis

unfortunately you need a DRB-II with the TCU adapter to get any kind of information from the TCU.

 

[kastein]

If you compare the settings, it looks like that's more a factor of TCU design and user comfort. They have the same solenoid selections listed for N, P, R, and 1st gear (in 1-2, 3, or overdrive.) My bet - the TCU leaves the solenoids in 1st gear for N/P/R so you won't feel a shift lag or lurch when you drop it in drive like you would if it was sitting in OD while in N/P/R.

 

[87manche]

If you compare the settings, it looks like that's more a factor of TCU design and user comfort. They have the same solenoid selections listed for N, P, R, and 1st gear (in 1-2, 3, or overdrive.) My bet - the TCU leaves the solenoids in 1st gear for N/P/R so you won't feel a shift lag or lurch when you drop it in drive like you would if it was sitting in OD while in N/P/R.

possibly. I guess no one will know until they dissect an AW4 valvebody.

I guess the easy way to test it would be to disconnect the TCU and manually switch the solenoids for a minute. Leave solenoid 1 off and see if reverse works.

 

[kastein]

I have one hanging on the wall in my workshop at home, but looking at all those passages makes me go :wow:

Reading through the FSM section with the hydraulic schematics for the AW4 will probably be way easier to understand, and even those are pretty confusing.

 

[87manche]

I have one hanging on the wall in my workshop at home, but looking at all those passages makes me go :wow:

Reading through the FSM section with the hydraulic schematics for the AW4 will probably be way easier to understand, and even those are pretty confusing.

The last auto trans I had apart was a 4sp electronic front wheel drive job from a Focus.

needless to say I'm done fixing automatic transmissions, if it dies it's getting a 5 spd swap.

note the jar of random bits from the valvebody on the right.

Good times reassembling that.

 

[Ecomike]

87mancha, that must be a typo in the manual. Sol #3 is only used to engage the TC lock up. That should be sol #1, not sol #3 in your earlier post.

 

[Ecomike]

The last auto trans I had apart was a 4sp electronic front wheel drive job from a Focus.

needless to say I'm done fixing automatic transmissions, if it dies it's getting a 5 spd swap.

note the jar of random bits from the valvebody on the right.

Good times reassembling that.

LOL, I had my share of fun rebuilding a 5 speed 1982 Nissan manual transmission. Spent most of my time building custom tools, and standing on my head at the bearing press. It was a nightmare for a manual T, made me want to switch to automatic, LOL!

IIRC, my 87, which has the TCU disconnected went into reverse last week end with no problem. So it begs the question, why do they leave S-1 engaged in R-?

I am in the process of swapping my 87 4x4 AW4 already with my spare. And I have the xxxx hundred page ATSG repair & service manual for the AW4.

Now the 89 2WD is acting up, which is what I started this thread about when the gremlins were attacking the igniton system 4 weeks ago.

I think Joe is right I need a priest, just not sure if it needs burial, last rights or an exorcism?:laugh3:

 

[87manche]

I suspect that Ken's right on the solenoid one engagement. They leave it engaged so that the first gear engagement isnt harsh

 

[lawsoncl]

If you compare the settings, it looks like that's more a factor of TCU design and user comfort. They have the same solenoid selections listed for N, P, R, and 1st gear (in 1-2, 3, or overdrive.) My bet - the TCU leaves the solenoids in 1st gear for N/P/R so you won't feel a shift lag or lurch when you drop it in drive like you would if it was sitting in OD while in N/P/R.

For the Renix at least (might be the later models too), the TCU has no clue if you're in Reverse or 3rd gear. I think it's just engaging 1 based on the speed. It does have an input from the NSS for (D) and (1-2) though. I wonder if you got going fast enough in reverse, it would try to upshift?

 

[Ecomike]

Had a 4 try, 6 second crank time each time, failed to start problem again in 40 F cold weather. This time I used a paper clip, shorted the CPS for about 5 seconds at most. It started first try in about 3 seconds. I am getting fonder of paper clips if this keeps up. May need to add them to my duct tape tool bag!

 

[cruiser54]

Bailing wire and bubble gum would also be a nice addition to your tool bag. LOL

 

[Ecomike]

Bailing wire and bubble gum would also be a nice addition to your tool bag. LOL

I keep the bailing wire handy!!! Bubble gum no. Hmm?

Do you know the story about how duct tape saved the Apollo 13 astronaut's lives?

Last night it failed to start after multiple (5-6 tries) 6 second cranks. It was about 40 F. I used a paper clip to short the CPS-ECU connection for 3 seconds. The jeep fired right up in just 3 seconds of cranking on the next try. Runs perfectly once it fires. CPS ohms out at about 225 ohms soldered into the circuit.


This morning:
It (89) cranked up and started in 3.5-4 seconds this morning, at 32 F! Forward gear worked right away, reverse took a few minutes to warm up, but never slipped, it just suddenly went into gear like a switch was flipped, so re-setting the TV cable brought back forward at a cold start in the morning, and I think several fluid transfusions and some Trans-x before draining may get the sticky gunk out and bring reverse back to normal (unstick it). The Tranny works like a brand new one, once Reverse pops into service, unlike the 87 that now has a bad 1st gear slip all the time, and a perfect reverse all the time.

So if I oval out the holes in a new CPS, how much metal is it safe to remove? How much closer can the CPS be moved to the flex plate? I may get a bigger hammer and just nudge/bend the current CPS a little closer. Seems to be an OK method to get it a little closer, very slowly, but I had serious doubts at first. I think one may need to re-tighten the bolts after the hammer shaft trick, to make sure it does not move later?

I still need to look into the lost brake lights issue next, before the gremlins hit the next areas. Got to try and keep up with these buggers!:banghead:

Since I was under the dash fiddling with the ECU connections recently, I will check the brake switch wiring first, before I go buy a new switch. IIRC I already replaced it, but too many jeeps, to recall for sure if this one was replaced yet.

 

[cruiser54]

Drill one of the holes out with the first bit that won't go through the existing hole. I think you can go to the one above that. We had a guy in our shop that would drill the hole a little bigger, push that end of the sensor down, and fire it up. If the sensor hit the flywheel, he didn't care. It "self clearanced" itself. Still worked fone. I do not endorse his method however.

 

[Ecomike]

I got the brake lights working, I must have knocked it down, out of position messing with the ECU connections last time, but something about the mounting on the Brake switch seems too loose. Will need to look at it further later.

Had several routine starts, no problems since last post, then this morning, 2 tries no joy, then shorted the CPS for 60 seconds, then 3 tries failed, then connected the DVM, first try no signal, or maybe .06 V max, second try got maybe .1-.15 V max, then third try got .26 V, fourth try it hit .36 V in 2 seconds and started. Did not try the capacitor this time. I wonder if shorting the CPS/ECU connection with power on (no start) might make a (the) difference?

Sure acts like the new AZ CPS has a discontinuity itself at some no starts. But once it starts, it never dies.

????


Planning to nudge it a little close to the flywheel again. Then if it continues to act up, I will install one of the new ones.

This is only the second time the DMM caught it giving out no signal or a very low voltage on a no start crank with the DMM connected.

Ambient was only about 50 F this morning. No rain, moderate humidity, so it is not following a cold or hot, or only rain high humidity no start (from a no spark & no fuel) pattern.

 

[Ecomike]

I have nudged it closer to the flexplate several times with the aid of a BFH (LOL, JK, it was a small hammer), and got the CPS cranking voltage up to .74 V peak.

Last 3 starts, 2-3 seconds, second one (cold overnight) 4-5 seconds, tonight (cold) apx 5 seconds, maybe 6, all on the first crank got it starter.

Still not convinced I am done with this gremlin, but it is looking better as the DMM got a rest today (LOL). And I still have the duct tape in reserve in needed!:laugh3:

 

[cruiser54]

That's why I like to test a CPS using a voltage test rather than a resistance test.
Remember I mentioned earlier that we found at the dealership that .35V could cause intermittent starting? Actually, maybe JeepTech gave us that spec. I'd have to look in my notes to be sure.

 

[Ecomike]

Got my 1987 AW4 dropped today, and got a look at the OEM renix CPS mounted in the spare AW4 I am about to use, and the AW4 I just pulled on the 87 (the 87 was the one that always starts, but only has .27 V AC signal strength).

Turns out the stock distance from the flex plate has a huge clearance in the neighborhood of 1/8" on my 87!!!!!!!!!!!!!!!!! Lots of room to move the CPS closer!