AW4 does not shift - help me finish troubleshooting

[bigalpha]

1. What do you make of the 'b' pin at the connector under the hood not registering anything when I connect it to 'f' pin; but getting a resistance when i connect 'f' pin to batt neg pole?

2. Can I have a gunky and malfunctioning NSS even if I experience no typical NSS symptoms? If so, will this have any impact on the tranny problem?

3. Is the TPS still alright, even if the Voltage is somewhat low?

4. Where does the wiring run to the solenoids? It goes down the firewall, then does it go over the top of the tranny?

 

[lawsoncl]

The FSM numbers the pins different, but I think I matched up your letters to its numbers. The pin B being the one marked ground. That wire and the one you'd call C go to the speed sensor. It does not connect to ground at the tranny, so unless you have the connector plugged in, I wouldn't expect to see ground on that wire.

Usually the first symptom of a really gummed up NSS on an OBDI Jeep is that the reverse lights don't work or it won't start with the shifter in park. I don't believe a dirty NSS will cause your symptoms.

I don't believe the TPS is your problem either, even though the upper voltage seems a bit low. You could unplug it just to see what happens. It should run although rough, but I don't expect the tranny to suddenly start working correctly.

The wiring runs down the firewall and across the top of the tranny and comes down the drivers side of the tranny. It should be easy enough to spot looking from the drivers side.

 

[bigalpha]

lawson, I was using the chart from here: http://www.teamkov.ath.cx/tcu.jpg.

I've already unplugged the TPS while jeep is running, but Jeep didn't run any different, really.

I'll check the wiring and make sure it's all intact. I guess the only course of action that's left is to test the solenoids directly.

 

[B.RAIDER]

I posted this back in thread #31:

Set your meter to ohms and touch the ground side of the battery to your engine block and then your ground strap on your firewall. I just did mine and I got 0 OHMS at both checkpoints.

Do this check and report both your readings there. That should tell what kind of ground you are getting at those points.

When I first checked mine I did have some resistance there. I don't remember the readings...they were something like .8 or 1.0 or something like that.
I took a wrench and lossened and tighted the connections mentioned at all four points to yield me the 0 ohm reading I have now.

 

[bigalpha]

I tested the neg battery terminal to the battery ground on the engine block and got .2 ohms.
I tested neg battery terminal to the strap on the firewall and got 1.2 ohms.

I didn't check the main ground that's under the oil filter. At the time, the engine was hot and I didn't wanna get burned. :flame:

 

[B.RAIDER]

I didn't check the main ground that's under the oil filter. At the time, the engine was hot and I didn't wanna get burned. :flame:

OPPS....I guess I missed that one :doh:.
I'll do some checking on the forum here ..... but I think the 1.2 is a bit high.

 

[B.RAIDER]

Use the ohm meter to test between the engine block and the battery ground, engine block and clean bare spot on the firewall, and the firewall and the battery ground all with the power turned off. They should all read less than 1 ohm. If one or more reads higher than 1 ohm you still have a ground problem.

I just found this, it was in the Renix High idle thread. At this time I don't know where he got that number (less than 1 ohm), but I hve read that somewheres else also.

 

[bigalpha]

I'll re-test my grounds and verify the numbers I got the first time. Heck, they could be different this time, considering the difference I get when I check the solenoids.

 

[B.RAIDER]

I'll re-test my grounds and verify the numbers I got the first time. Heck, they could be different this time, considering the difference I get when I check the solenoids.

There are a lot of threads where the ground issue have beem discussed. I just put OHMS in the search box and found the one I mentioned. It's just one of many.
Here's another quote for a TPS thread on resistance at the battery grounds, I think it was:

Almost 1 ohm resistance does seem a bit high, particulary given how many sensors probably share this ground.

I'm sure those two guys can I quoted from can tell you the source from where they got those numbers.

I used two different meters when I was checking mine, one cheap one and one supposedly a very good one, and I got the same readings within a point or two of each other.
It could very well be bad solenoids. But I'm still leaning towards a wiring related problem.

 

[bigalpha]

Alright. I'll test the grounds, record the measurements and clean them up a bit. Do you think a bad ground can cause my issue?

 

[B.RAIDER]

Do you think a bad ground can cause my issue?

I believe it could be related to your readings your getting when you test the solenoids.
You have to remember that alot of electrical components use the engine block and chassis as the ground source to the battery.
But, as I have stated I still think you have a wiring issue somewhere.

 

[bigalpha]

Assuming it doesn't rain today after work, I'm going to try to crawl around underneath and follow the wiring and make sure it's in good shape. For all I know, it could be completely gone, lol. I'll also check/clean grounds too.

 

[B.RAIDER]

Assuming it doesn't rain today after work, I'm going to try to crawl around underneath and follow the wiring and make sure it's in good shape. For all I know, it could be completely gone, lol. I'll also check/clean grounds too.

LOL... It's a dirty job :shocked:.......but..........somebody's gotta do it.:laugh:
I hate electrical problems.... particularly when they're my problems:explosion.

 

[bigalpha]

Yeah, it's going to be filthy dirty, especially since there is some oil leak around my oil filter. Maybe I can get my woman to do it, haha.

 

[B.RAIDER]

Any more findings?
Or ..... are you giving it a rest for a while? (been there ... done that...LOL)

 

[bigalpha]

Ah sorry. Weather has been kind of crappy lately. I should be able to crawl under there again tomorrow and double check the wiring.

I gotta work myself up to pulling the pan and directly testing the solenoids. I just gotta get the fluid and RTV and rip the pan off.

Do you know if solenoids from 1998 will work in a 1995 AW4? I don't know if they made any changes that would affect that or not.

 

[bigalpha]

Just an update ... I'm waiting on getting some solenoids before I pull the pan and such because my Jeep is my DD for right now; this way I won't have to pull the pan twice if the solenoids are bad.

I'm getting solenoids from a 1997.

 

[boojo35]

Just to help you guys out..... the best way to check a ground is by testing the voltage drop.... lets take the instance of a bad battery ground cable.... say the cable was broken through but still had one copper strand intact.... if you check it with an ohm meter it would still read very low and good resistance..... to test it with the voltage drop method you hook one meter lead on the battery negative post and the other lead at the other end of the same ground cable.... turn the key on and lights etc..... the cable needs to have a load on it..... have the meter set on the dc voltage scale.... if the cable is good, the reading will be less than .5v...... if you have a higher reading you are losing voltage through that cable..... the volt meter is actually reading the amount of voltage that is lost accross the circuit.... if you think back to the cable with only one strand of copper left, it will not carry a large load or current and will fail this test, but will pass a resistance test..... the voltage drop test can be used on power wires or ground wires....