CDL Will Not Engage.... (1 Viewer)

[izzyandsue]

My CDL wasn't engaging and I fix it this way:

Izzy's amateur hour

If you look up on passenger side to the where the connector is (flaslight), there is a green wire that was being chafed by the linkages, until it broke. You may have the same and it was as simple as reconnecting and protecting it.

If you have to jump the connector to see if the CDL is inded moving, check the bottom of page 4 of my post, I have some pics showing that same process with a wire jumper. Good luck, hope is something simple like that, a wire or just cleaning of the sensor.

 

[WarWagon]

Thanks....I double checked and I did indeed swap out the correct switch. I'm going to throw in another bulb and go back over the wiring as soon as Noah's Ark pulls out of North GA

 

[george_tlc]

PULL THE CONNECTOR, WIRE LINK ACROSS THE 2 PINS OF THE CONNECTOR... Does the CDL light on the dash come on and the ABS light? Engine off, key to ON.

cheers,
george.

 

[jcwhitty]

Hi George....how is everything I Sunny Sunnyvale? I grew up in East San Jose, Alum Rock area, but have resided in the Portland Oregon area for the last 30 some years.

I also am trying to troubleshoot my CDL. (1994, I have done the 7 pin mod, factory lockers)I jumped the connector as you suggested, and the two indicator lights, ABS and Locked Center Diff came on. I was then able to then lock the rear end, though the dash indicator light continued to flash, though I know it was locked. (just in case this might have any relevance). So, I cannot hear the relay click, so I figure there are two possible issues. 1) The CDL switch in the dash is bad, or 2) The relay is bad. I would like to eliminate the switch first, but do not know what to jump on the connector in order to bypass it.

Any assistance would be appreciated, or anything I missed? Thanks in advance.

John.

 

[ajax1]

So do what George says, jump that switch, if it lights up bad switch no light wire somewhere to that switch

 

[ppc]

Each of the lockers, front, center and rear have a sensor switch when the lock occurs. Just as you jumpered the center sensor to test the dash lights you can do the same front and rear. If the dash lights go solid and you confirm that the lockers actually engage then you have zeroed the problem to the sensor switches. You can replace them or try to rejuvenate them by removing them spraying WD40 into the ball end and working the switch until they show good with a multimeter.

 

[jcwhitty]

Thanks guys for the responses, though I still feel the problem with the CDL could originate from the Center Differential Control Box. All of the threads I have read indicate that the relay in the CDL Control Box makes noise/click when energized. I have the kick panel out, the ABS Control Box out of the way, and when I push on the dash CDL switch, there is not a peep from within that box. I did some further tests, and it would appear that the Dash Switch is working, so I am assuming that the problem lies with the CDL control box.

Phil: Good information for me regarding the dash lights continuing to flash. Once I get the CDL problem solved and corrected, I will work on the those sensors.

John.

 

[george_tlc]

^ have you downloaded the 1996 EWD? Page 150 has the center diff lock wiring/circuitry. I would thing it should be essentially the same for your 94.

It shows the various fuses and relay control units. And yes, with key to ON, engine off, you should easily hear the CDL relay module click when you press the CDL switch in and then back out.

I presume the CDL was working via the L range lever BEFORE you did the pin 7 mod??

Sunnyvale is doing fine, though there's wholesale knocking down of old buildings and termite mounds (LARGE multi-storey apartment complexes) are going up everywhere in the south bay, not just Sunnyvale. Hard to beat the weather down here...

cheers,
george.

 

[jcwhitty]

Hi George....Thanks for the reply.

First off, the CDL has been working fine up until I tried to engage it the other day.

Yes, I do have the EWD for 96, and in fact there is one minor difference in the 94. If you look at the connector for the CDL Control Box (C 5), what would be terminal 6, but shown as an X, is in fact a terminal. When I somewhat tested the dash CDL switch, with ignition power on, switch off, there is power to both 3 and 9. When the dash CDL switch is on, there is now power to 3 and 6, no longer 9. From these changes in power status, I have assumed that the dash switch is working properly.

I have the CDL control box in hand. I have removed the face plate, but it appears to be difficult to actually remove the board from the case without cutting the case open. There is burnt smell emanating from the box. Now that I have it in hand, is there a way I can test the CDL control box and relays. I can somewhat follow the schematics, but am not that versed in electronics, and would be afraid to damage something.

I was going to test it at the connection to the transfer case, but what a bear to get to that connector, so I chose this route. I really want to confirm that it is not the control board before I try to screw with the actuator.

I was down in Monterey through mid December, and El Nino had not arrived yet...yes, the weather is nice!

Once again, certainly appreciate your help.

John.

 

[jcwhitty]

Hi George....Thanks for the reply.

First off, the CDL has been working fine up until I tried to engage it the other day.

Yes, I do have the EWD for 96, and in fact there is one minor difference in the 94. If you look at the connector for the CDL Control Box (C 5), what would be terminal 6, but shown as an X, is in fact a terminal. When I somewhat tested the dash CDL switch, with ignition power on, switch off, there is power to both 3 and 9. When the dash CDL switch is on, there is now power to 3 and 6, no longer 9. From these changes in power status, I have assumed that the dash switch is working properly.

I have the CDL control box in hand. I have removed the face plate, but it appears to be difficult to actually remove the board from the case without cutting the case open. There is burnt smell emanating from the box. Now that I have it in hand, is there a way I can test the CDL control box and relays. I can somewhat follow the schematics, but am not that versed in electronics, and would be afraid to damage something.

I was going to test it at the connection to the transfer case, but what a bear to get to that connector, so I chose this route. I really want to confirm that it is not the control board before I try to screw with the actuator.

I was down in Monterey through mid December, and El Nino had not arrived yet...yes, the weather is nice!

Once again, certainly appreciate your help.

John.

Correction......there is not any burnt smell!

 

[george_tlc]

Here's a schematic of the relay:

Take the CDL relay module out of the vehicle and get a few wires for testing purposes (a power supply would be good, but your battery will work if you are CAREFUL).

If you apply 12V to pin 7 and connect GND to pin 2 then the top left relay should engage (click). The coil is the coiled wire looking part of the picture. There are 3 relays in that module. Apply 12V to pin 7 and connect GND to pin 5 and the bottom right relay should click.

With the 12V to pin 9 (remove from pin 7) connected, if you take the GND wire and use it to touch A (pin 10) then the bottom left relay should energise (click). You can go further and use a meter on ohms range to check if each of the contacts in the relay are closing/opening appropriately as you power each coil up. Note that some of the relays (e.g. the top left one) has the contacts closed with power NOT applied and opens when power is applied.

NOTE where I say 12V I mean *POSITIVE* 12V. The relays have diodes across the coils, so if you connect them 'backwards' you WILL blow the diodes...

Anyhow, I'm off my computer for a few hours, so if you have questions, ask, and I'll try to answer when I get back later this afternoon.

cheers,
george.

 

[bloc]

The difference between 94 and 97 is as follows.

97 only has one wire running from the dash switch to the CDL relay, it is Black, on pin 9. There is a jumper in place of the dash switch that gives this +12v through the 10A "gauge" fuse any time the ignition is on. It appears this makes it so that the transfer lever being in Low is the only thing that engages the CDL, as stock on a 97.
94 has two wires from the dash switch, one black on pin 9 that serves the same function as on a 97, and a Black/Red wire on pin 6. There is a note for a jumper between Black wire pin 9 and +12v as in the 97 labeled "W/ABS". The black/red wire is labeled as "W/O ABS" on the 94 EWD. Also, w/o ABS gets the CDL dash switch, it appears.

So it seems the 94 chassis, even if it came with ABS, is wired with the 'W/O ABS' wiring for the CDL.

 

[jcwhitty]

George and Bloc......Thanks for the input.

First off, my 94 does have ABS, and did not come with the CDL.

Secondly, my test results. I did not test the continuity.....not a lot of room inside that connector, and once again I was concerned that I might, "light something up!" First I applied 12v to 7, ground to 2, and it energized. (clicked). The next was ground to 2 and 5, power to 9, no click. Next, power to 9, ground 2 and 10, click. I am thinking that the relay which did not energize, is the one which initiates "locking".

And another question: What is 10 amp "gauged"?

Let me know the diagnosis of my test procedures!

Thanks, John.

 

[jcwhitty]

Holy cow....this little box is filled with gold! $180.00 for a new one. Maybe I should take a chance on a used one. in fact, I can get two for probably 50 bucks off ebay.

 

[george_tlc]

Jcwhitty, no, you didn't quite test the relays correctly (and my description above wasn't quite right, I'll edit/correct it)...

1) Connect +12V to 7 and GND to 2 and the top left relay should click.
2) Connect +12V to 7 and GND to 5 and the bottom right relay should click.
3) Connect +12V to 9 and GND to 10 and the bottom left relay should click.

That will at least confirm that the relay coils and mechanism function. Doesn't prove if the contacts are good though since you would need to measure continuity with an ohm meter etc while activating the coils.

cheers,
george.

 

[Brimley]

"Thanks for the advice guys, and yeah I see now where I switched out the damn 4L switch, which was working fine

I see why troubleshooting and tracking down this issue is such a headache. I'm looking at the FSM now so hopefully I'll get this figured out sooner than later.

Merry Christmas!"


Been there and done exactly that. Make sure and and search the generic rep $16 not $70 like an ome one.

 

[jcwhitty]

Okay, that did change things. All of the relays clicked, which leads me back to the switch. I certainly would have heard the relay energize when I first push in the dash switch, but I did not. Earlier I mentioned which terminals showed hot or not when I pushed in the dash switch, which I will study and see if I can figure out what is happening. Thanks for your patience, and direction.

John.

 

[george_tlc]

The relays may also not click if there's something wrong with the GND path to the coils of the bottom two relays.

The relays get their GND via the limit switch in the CDL motor. The design is a sequencer made up of the 2 relays and the limit switch. Basically the 'circuit' will power the motor one way with one relay until the limit switch toggles, it then stops applying power to the motor. The other relay is then ready to be powered via its coil (since the GND toggled to it) until the motor reaches the other extreme and the switch toggles again. Basically it's a relay based logic circuit. The motor is powered +/- one way and -/+ the other way, the contacts of the bottom 2 relays are designed to flip the +/- polarity to drive the motor forward or backward since its a DC motor.

So, you need to ensure that Pin 5 has Ground when Pin 10 doesn't and vice versa. Ensure that the ground connection on the motor connector (pin 4 in the picture) goes solid to ground (the E22 EC/EC1 ground splice/body connection).

Pin 2/3 on the motor connector is where the +/- 12V or -/+ 12V is applied to the CDL actuator motor to drive it one way or the other way (engage/disengage).

That's another failure possibility in addition to the CDL console switch having some issue.

cheers,
george.

 

[jcwhitty]

You definitely know your electrical! After reviewing the schematics, I noticed that the Transfer Case Neutral Position Switch is also on this ground, and it reminded me that the other night when I shifted the transfer case into low range, no dash lights came on when in the neutral position. We may have found the cause, now all I need to do is track down where this ground has gone bad. I will do more reading and learn more about the schematics!

John.

 

[jcwhitty]

And by the way, Happy New Year, everyone. Thanks for all the support over the years!