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All working good now, CDL engages by the dash switch and when shifting into 4 Low.
CDL Will Not Engage....
- Thread starter WarWagon
- Start date
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Good to hear. Mine's a daily driver and CDL hasn't worked in a while (never exercised). Relay is good, switches (at mechanism) test good; just didn't want to drop the xfer case to rebuild motor OR have it engage and not disengage.
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I’m sure I just got lucky and it may be one of those things that resurface. I sold this 80 back in 2012 and purchased it back in October. I have about 1/2 mile of unpaved road upto the house and been exercising the diff locks just about every time I’ve driven it. They almost engage immediately now. I’m thinking back to this situation and I don’t think I was at a complete stop when I shifted to neutral to engage the 4 low. I’m wondering if that had something to do with the issue today.
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As mentioned in my last post, my concern the issue would resurface has come to fruition. Over the past several months I’d have occasion where I’d put the 80 in 4 low or press the dash CDL switch and would not get ABS or DIFF lights on dash. The 80 goes into 4 low, but do not know if CDL is engaging. It was an intermittent issue.
Also had occasion where the rear diff lock would not engage (continues to blink with no clicking sound behind glove box) but front diff lock engages immediately (with click behind glove box). From searching, it appeared the 4WD ECU would be the culprit and I just replaced it with a new OEM unit.
Haven’t driven the 80 in a couple weeks and went out to test the new 4WD ECU. Moved lever to 4 low and no indicators appeared on the dash. Drove down a dirt road and still no indicator lights came on. Tried listening for any clicking/whirling sounds when pushing CDL switch and actuating the 4HI/4LO lever with engine off and key in “on” position and there is no sound (and still no dash lights).
Since I’m not hearing any sounds when engaging the CDL, my research is leaning me towards the trans relay in driver side kick panel as the next possible option to replace. Anyone think differently?
TIA
(update, crawled underneath and sprayed the wire connections for the indicator switch, located on the front of the transfer case, with WD40 and reconnected. The lights are now coming on and I’m hearing the relay clicking in driver kick panel. Is there a relationship between the indicator switch and the relay operating properly?)
Also had occasion where the rear diff lock would not engage (continues to blink with no clicking sound behind glove box) but front diff lock engages immediately (with click behind glove box). From searching, it appeared the 4WD ECU would be the culprit and I just replaced it with a new OEM unit.
Haven’t driven the 80 in a couple weeks and went out to test the new 4WD ECU. Moved lever to 4 low and no indicators appeared on the dash. Drove down a dirt road and still no indicator lights came on. Tried listening for any clicking/whirling sounds when pushing CDL switch and actuating the 4HI/4LO lever with engine off and key in “on” position and there is no sound (and still no dash lights).
Since I’m not hearing any sounds when engaging the CDL, my research is leaning me towards the trans relay in driver side kick panel as the next possible option to replace. Anyone think differently?
TIA
(update, crawled underneath and sprayed the wire connections for the indicator switch, located on the front of the transfer case, with WD40 and reconnected. The lights are now coming on and I’m hearing the relay clicking in driver kick panel. Is there a relationship between the indicator switch and the relay operating properly?)
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Bumping this CDL thread as I'm having the same issues on my 2.5" lifted 1995 80 series (with no gear, rear seats, running boards, oem grill bumpers) all removed, so more like 3" lift with camber on the differential that I haven't corrected besides installing a Delta panhard lift bracket - if anyone knows what part of the car is suffering the most from this please let me know.
Problem: No CDL light, no ABS light, no A/T light when moving between 4L-N-4H. CDL feels locked and drivetrain winding when actuated into D and 4L (actuating = In N, moving lever from 4H to 4L is bumpy - and when moving from N to D or R car lurches with loud noise and shifting accelerating from first to second gear causes a gnarly lurch)
Attempt 1: Replaced front CDL sensor with no washer -
1) no changes.
Attempt 2: Replaced rear CDL sensor with thicker washer -
1) CDL light and and A/T light
2) no ABS
Attempt 3: Replaced rear 4L sensor with thicker washer and added CDL switch in dash
1) no CDL, no ABS, and no A/T light
2) no ABS
Driving to the gas station with the CDL switch in dash pressed in randomly turned on CDL light only, pressed it again and it turned off, and wouldn't turn back on
Attempt 4: Cleaned all electrical contact points, pushed in the balls in sensors back and forth, added thinner oem? washer to front CDL sensor, replaced new rear 4L with the old one
1) no CDL and no ABS
2) A/T light on in P and N
Drove around a dirt road in S shapes in 4L trying to shake it up but nothing, and pressed the switch in while driving a bunch but I just bought 2 oem sensors and plugging them in with oem washers to see if that works
Problem: No CDL light, no ABS light, no A/T light when moving between 4L-N-4H. CDL feels locked and drivetrain winding when actuated into D and 4L (actuating = In N, moving lever from 4H to 4L is bumpy - and when moving from N to D or R car lurches with loud noise and shifting accelerating from first to second gear causes a gnarly lurch)
Attempt 1: Replaced front CDL sensor with no washer -
1) no changes.
Attempt 2: Replaced rear CDL sensor with thicker washer -
1) CDL light and and A/T light
2) no ABS
Attempt 3: Replaced rear 4L sensor with thicker washer and added CDL switch in dash
1) no CDL, no ABS, and no A/T light
2) no ABS
Driving to the gas station with the CDL switch in dash pressed in randomly turned on CDL light only, pressed it again and it turned off, and wouldn't turn back on
Attempt 4: Cleaned all electrical contact points, pushed in the balls in sensors back and forth, added thinner oem? washer to front CDL sensor, replaced new rear 4L with the old one
1) no CDL and no ABS
2) A/T light on in P and N
Drove around a dirt road in S shapes in 4L trying to shake it up but nothing, and pressed the switch in while driving a bunch but I just bought 2 oem sensors and plugging them in with oem washers to see if that works
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If you’ve read through this thread you’ll see many who throw the position sensors at the vehicle with zero change. Stop replacing sensors as it’s expensive and easy to diagnose. Cross the plug on that sensor with a bit of wiring and it will “fool” the ECU into thinking mechanical things are moving and the sensor is reading.
Most issues you find with 80’s that have CDL and Locker issues is these components are gummed up and never used. They either need to manually be pulled out and cleaned, or at least be moved manually to get a good connection on the inside trace wires.
I can’t stress enough to take a 3” piece of wire and cross the CDL sensor plug which will immediately show you if there are any wiring issues or module issues as the cluster will light the yellow center diff lock symbol and ABS light. So it’s a simple bulb check but also the 4wd ECU will enable locker operation at that point so you can check those things.
Sorry forgot to add that I crossed the wiring harness with paper clip and the CDL light turns on - no ABS light - only with the front CDL sensor. If i cross the rear CDL sensor - the CDL and ABS light do not turn on.
In that case also cross the sensor for the Low position indicator. That should tell the truck it’s in Low range and CDL locked. If the Low range light is out which is possible I’d try to actuate lockers with an axle in the air and spin tires by hand to see if they lock. It should only take a few degrees of a turn with no load and you’ll immediately hear a click and then the tires will become hard to turn by hand. Just keep at it and you’ll get to the bottom of this!
Thanke Ze! What do you mean by "Low range light is out"? Is low range light different than CDL light? I thought that the 4L sensor only controls the A/T light in the dash which is currently working in P and N
No you’re right. There is no low range light, but if that sensor is dirty or there is an issue in the T-case not shorting the sensor plunger. Crossing the terminals with wire manually will take it out of the equation.
Yeah I crossed terminals:
-front CDL sensor only - CDL light on, no ABS light.
-rear CDL sensor - no lights
-rear 4L sensor - A/T light on
Also when I shift from to 4L - going from neutral to drive the car bucks like crazy is that normal lol
-front CDL sensor only - CDL light on, no ABS light.
-rear CDL sensor - no lights
-rear 4L sensor - A/T light on
Also when I shift from to 4L - going from neutral to drive the car bucks like crazy is that normal lol
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Yes it’s normal for the gear engagement in low to be harsh. It’s magnified if your idle is high as well. Normal warm idle is around 650rpms.
I’m recommending to short the CDL sensor when it shows it’s in the locked position as well as shorting the sensor that is pressed when you shift to low. Both of those sensors should be shorted to illuminate both center lock and ABS lights on the dash. This also enables rear and front lockers to be selected. If you are shorting both of those and you cannot engage lockers then you have either upstream electrical problems or multiple locker actuators that are faulty.
You really need to get reading the FSM. The terminology you are using is not correct and confusing you and others.
The proper terminology for the three sensor/switches on the transfer case:
Center Diff Lock Indicator SW - located on the front of the transfer case near the front drive shaft. Its only function is to detect when the locking collar is in place confirming the lock. It connects directly to the CDL dash light and sends a ground signal to the ABS to disable the system and turn on the ABS dash lite. Both lights show illuminated simultaneously. If both dash lights are not working then is most likely a dirty/failing sensor. If the ABS doesn't light then there is a fault with the ABS computer.
Transfer L4 Position - located on the rear extension of the transfer case. From underneath the vehicle looking forward it is on the right side at
approximately at the 1 O'clock position. This should be the first sensor to get repaired. IF you added the CDL dash switch you should be able to lock the CDL in high range. If you have done the Pin 7 mod then the dash switch is the only way to lock in both high and low range. Without the pin 7 mod switching to low should will still enable the CDL.
Transfer Neutral Position SW - located on the rear extension of the transfer case. From underneath the vehicle looking forward it is on the right side at
approximately at the 11 O'clock position. The only purpose of this sensor is light the AT/P dash light to warn the driver that even with the transmission park the vehicle can roll freely when the transfer case is in neutral. This would be the last of the sensors to fix as it isn't related the CDL functionality.
All of these sensors operate mostly independent of each other so to make debugging easier just deal with one a a time. You seem to mixing up the purpose of each and too worried about thick or thin washers. You really need a multi-meter and start checking for loose connections and broken wiring.
Most importantly all of this diagnosis can be done without starting the motor so you should be hearing relays click and the whirling sound the CDL actuator makes when activated.
Didn't do anything but drive it today - now it all seems to be working perfectly ¯\_(ツ)_/¯
so i had this issue. and 2 weeks ago while out on the trail i drove up on a side hill got under the rig pulled that sensor, pushed the plunger in and out about 30 times reinstalled and over the course of the weekend the CDL would flicker on and off at first but after two days of this it would just stay one when commanded to do so by the switch, high or low. thats my story.
did you ever solve this? I just also replaced the sensor and it changed nothing and was curious what you may have done nextView attachment 1181052 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
i can use it. i pulled it and cleaned it some and it kni nda works. it sometimes still flickers but i have not bought another one. just use and know it sometimes flickers at first. but after its on for a ;little while it just stays on,.