Flickering CDL on a x3 Locked (1 Viewer)

[aktundra]

Just did a rather long trail run in my 1993, after the truck sat for about a year. I noticed the CDL flickering on & off from time to time (which of course, turned off the F&R axel lockers)

I could not see a distinct pattern: cobblestone trail, water crossings, hill climb, or mud. Over the course of approx 15 hours on the trail, seemed to be somewhat random. Didn’t fail at particularly bad times, just bothersome.

Oh, and one other potentially relevant point. I have plugged in a CDL switch (had the dash apart for a radio install), but not done the 7th pin mod or any other mods to the CDL system. Whether the switch was pressed or not, did not seem to make a difference.

Anybody experience something similar?Any suggestions where to start looking for a remedy ?

 

[george_tlc]

1st guess would be the CDL switch/sensor. Through lack of use, it can become 'tempermental'.

CDL Sensor/Switch

You can rejuvenate it or just buy an aftermarket replacement. Pretty cheap. Can even find them on amazon. Of course it could also be your head gasket about to blow (j/k).

cheers,
george.

 

[LandLocked93]

I thought the switch was the 7-pin mod.
What else is there to do?
So when the CDL dash light flickered, the associated systems (f/r locks, ABS) responded to it?

 

[jonheld]

I thought the switch was the 7-pin mod.
What else is there to do?
So when the CDL dash light flickered, the associated systems (f/r locks, ABS) responded to it?

The transfer case has 3 switches that are physically mounted on the housings.
L4 position switch on rear extension housing.
Neutral position switch on rear extension housing.
Center diff lock indicator switch on front extension housing.

The diff lock ECU "sees" the closure from the CDL indicator switch on the transfer case and that's what throws the CDL tally lamp on the dash as well as the logic for the F/R factory diffs. If the switch on the transfer case (or associated connections) are questionable, then you get blinking lights.

 

[LandLocked93]

The transfer case has 3 switches that are physically mounted on the housings.
L4 position switch on rear extension housing.
Neutral position switch on rear extension housing.
Center diff lock indicator switch on front extension housing.

The diff lock ECU "sees" the closure from the CDL indicator switch on the transfer case and that's what throws the CDL tally lamp on the dash as well as the logic for the F/R factory diffs. If the switch on the transfer case (or associated connections) are questionable, then you get blinking lights.

^^ @aktundra

 

[Travis 76]

Installing the switch just gives you the advantage of being able to lock the center diff in high range. The 7 pin mod stops the automatic locking of the center diff in low range, meaning you will have to use the button in low range also. Or you can be in low range with the center diff open.

Mine was blinking last time I used it, I turned it off then on at a complete stop, drove slow until it engaged then it was fine.

 

[LandLocked93]

Mine was blinking last time I used it, I turned it off then on at a complete stop, drove slow until it engaged then it was fine.

Yes, there is a procedure (back of ds sunvisor) for engaging the locks and it isn't 'on the fly' engagement.
I think this is cause for some experiencing what they think is questionable functionality, especially if they are used to the system in much newer Jeeps.

 

[jonheld]

CDL can be locked/unlocked at any speed as long as you're not slipping any wheels. I routinely exercise the CDL at least once a month on a straight section of highway.

 

[LandLocked93]

CDL can be locked/unlocked at any speed as long as you're not slipping any wheels.

Only because of the 7p mod yeah? Otherwise without the switch, you're stopping completely to shift into low range, which engages the CDL (plus a little extra back and forth).

I routinely exercise the CDL at least once a month on a straight section of highway.

I need to exercise more too. And the axle locks. Come cold, they get all arthritic.

 

[ppc]

Only because of the 7p mod yeah? Otherwise without the switch, you're stopping completely to shift into low range, which engages the CDL (plus a little extra back and forth).

I need to exercise more too. And the axle locks. Come cold, they get all arthritic.

The "Pin 7" mod ONLY disables automatic locking in low range at the same time not changing transmission shift points, nothing more nothing less. It has nothing to do with locking the CDL at speed either in high or low range. If you don't have the dash switch then you do not want to do the Pin 7 mod.

 

[Squash]

Pull the cdl sensor and if you have a second person to watch the dash or even a video camera...engage the ball of your sensor.
Otherwise pull the plug and insert a piece of wire into both ends.
If your dash light is solid then suspect the sensor. Otherwise take out and swap a known working sensor from the front diff actuator.
Be certain to always check for a second sensor washer before any reinstallation because that extra thickness of washers can give your unit the flickers.

 

[LandLocked93]

The "Pin 7" mod ONLY disables automatic locking in low range at the same time not changing transmission shift points, nothing more nothing less. It has nothing to do with locking the CDL at speed either in high or low range. If you don't have the dash switch then you do not want to do the Pin 7 mod.

Ok so you are saying "7 pin mod" and "pin 7 mod" are two different things, correct?
In as much as the "7 pin mod" is simply adding the CDL switch to a truck that didn't come with one.
And the "pin 7 mod" affects the functionality of the CDL system such that it disables auto-lock of the CD when shifting into low range.
Do I have that right?
And that the CDL switch - by itself - cannot disable the auto-locking feature. The "pin 7 mod" must also be accomplished to have this 'feature'?

The CDL switch in my '93 has full control over when the CDL locks, in low or hi. So not asking for guidance. Just want to understand (or confirm) that there are in fact 2 separate procedures for making this control available. Guessing the "pin 7 mod" is accomplished somewhere other than in, on, or near the CDL switch? There is nothing special about the switch in my truck. Came with, from PO. But he did say he had it added some years ago.

 

[jonheld]

Ok so you are saying "7 pin mod" and "pin 7 mod" are two different things, correct?

No. For some reason people say "7 pin" when it is actually only pin 7 of connector C5 that is getting modified. It is the "pin 7 mod" and has always been the "pin 7 mod".

 

[LandLocked93]

No. For some reason people say "7 pin" when it is actually only pin 7 of connector C5 that is getting modified. It is the "pin 7 mod" and has always been the "pin 7 mod".

Fascinating.

Ok, back to you, OP. A thousand pardons for the hijack. lol

 

[aktundra]

It’s an old thread, but I guess about this time of year, I have CDL issues. Just got back from some long, tough off road trips (4x97 miles).

After the 1st 2 trips, my CDL stopped working. Everything covered in mud down below, but banged a few times with a big crescent wrench, in the general vicinity of the CDL (that’s how I got the rear locker “fixed”), came on for a few minutes, then nothing again.

I have done an LS swap, and have the toyota Tcase (the CDL and all the necessary switches for the lockers are on the Tcase) mounted to a Chevy 6 speed.

For about a year, I had the CDL working completely stock. Then it was flakey, so I did the Pin 7 mod, and again it worked fine until now.

I think I need to get another CDL assembly, but I wonder the role of the neutral position switch, on a Chevy tranny, with the Pin 7 Mod.

My question for the forum gurus: if I have done the Pin 7 Mod, does the Neutral Position Switch have any role in engaging the CDL ?