ABS and CDL Light Always On - Losing My Mind 1995 FZJ

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1995 FZJ80

Sorry if this has been posted or talked about before, but no matter how much I have searched, I can't find anything about it.

We bought this 80 series at our shop, and after inspecting everything, we found out that the previous owner had removed the CDL and ABS bulbs out of the dash. After installing them, we found that the CDL locker was broken. Thought that would solve the issue, but no. Upon further investigation, the center diff would still not lock, even though the actuator was working. After pulling the T-case out and apart, the shaft fork was not even attached to the sleeve. Finally, everything is together, the truck goes into 4lo and the center diff locks as it should, and everything seems happy, except, I am still getting the ABS and CDL light on the dash, no matter what position the actuator is in, and I have swapped the sensors on the T-case with known good ones, still the same issue. Changed out the relay for the center diff, no luck, and also tried a known good ABS computer, but still no luck. I have been tracing wires to check for shorts, or any issues with no luck yet.

At this point I just feel like I need some insight from you cruiser heads. I feel like I'm chasing my tail and not making any progress. Any suggestions or insights would be greatly helpful.

Thanks all
 

ppc

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The indicator lights for the CDL/ABS are completely divorced electrically from the CDL actuator, relay/ECU and associated wiring. The sensor on the front of the transfer case is the only control. point Have you disconnected the plug and shorted the terminals together on the wiring harness. This should activate the dash lights with the key on. If that does not turn the lights on there is a wiring issue. The sensor switch just provides a path to ground to illuminate the lights. If the lights illuminate then then pull that sensor switch out and activate the ball switch manually. If that lights the dash indicators then the problem is within the transfer case with the actuator not properly adjusted or the depth of the sensor is not correct as in the incorrect part. With the sensor switch out you should be able to look into the hole and see the movement of the actuator as it engages/disengages.
 

Squash

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The indicator lights for the CDL/ABS are completely divorced electrically from the CDL actuator, relay/ECU and associated wiring. The sensor on the front of the transfer case is the only control. point Have you disconnected the plug and shorted the terminals together on the wiring harness. This should activate the dash lights with the key on. If that does not turn the lights on there is a wiring issue. The sensor switch just provides a path to ground to illuminate the lights. If the lights illuminate then then pull that sensor switch out and activate the ball switch manually. If that lights the dash indicators then the problem is within the transfer case with the actuator not properly adjusted or the depth of the sensor is not correct as in the incorrect part. With the sensor switch out you should be able to look into the hole and see the movement of the actuator as it engages/disengages.
X2 on removing sensor and inserting a wire clip, just cut and strip a wire, light or no light.
If you get a light then check to see that there isn't a second crush washer as this is enough to keep the sensor from activating.
Lastly if the wire completes the circuit and or depressing the ball works then the motor may not be properly clocked.
 
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X2 on removing sensor and inserting a wire clip, just cut and strip a wire, light or no light.
If you get a light then check to see that there isn't a second crush washer as this is enough to keep the sensor from activating.
Lastly if the wire completes the circuit and or depressing the ball works then the motor may not be properly clocked.
So, We went ahead and got all brand new Toyota sensors x3, and the light is still on. Sounds like we might have to start tracing the entire harness. Sounds like there is something shorting to ground or some kind of connection where there shouldn't be.
 
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If you remove the plug on the front extension housing for the switch, the CDL and ABS lights should go off.
If they remain on, then there is a short between the 2 wires for the plug.
 
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If you remove the plug on the front extension housing for the switch, the CDL and ABS lights should go off.
If they remain on, then there is a short between the 2 wires for the plug.
Thats what it has to be. I pulled the codes, and I'm getting ABS code 48. We are down to tracing the entire harness trying to find the short. I will definitely post what I find out. I saw a couple other threads with code 48 with no report of what was causing it.
 
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Bump.....


I can't for the life of me find any shorts. I was trying to see if I can just run my own harness down to the switch, but since its all tied into the abs circuit, and a few others that is proving to be difficult. Am I way overthinking this?
 
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Sub divide the issue. If the ABS computer is detecting an error, the ABS light will remain on indicating that there is an error. ABS will be inactive.
Repair the error first and get ABS functional.

The switch circuit for the CDL is pretty simple. All it does is ground a pin to light the CDL light and turn off ABS. So somewhere between the switch on the transfer case and the ABS computer, there is a short to ground keeping the CDL lamp illuminated, or there is a malfunction of the ABS computer which is shorting that logic line to ground.
Connector A13 pin 19.
 
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Sub divide the issue. If the ABS computer is detecting an error, the ABS light will remain on indicating that there is an error. ABS will be inactive.
Repair the error first and get ABS functional.

The switch circuit for the CDL is pretty simple. All it does is ground a pin to light the CDL light and turn off ABS. So somewhere between the switch on the transfer case and the ABS computer, there is a short to ground keeping the CDL lamp illuminated, or there is a malfunction of the ABS computer which is shorting that logic line to ground.
Connector A13 pin 19.
Yeah it’s tripping me up. The abs light stays on even with the ABS computer unplugged. Even with the 4wd relay disconnected as well. I’ve been tracing the harness looking for a short to ground for the last few days.

I have the FSM and the factory wiring book as well. Tracing all of those circuits, I still can’t seem to find the fault.
I’m gonna keep digging though.
 
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Yeah it’s tripping me up. The abs light stays on even with the ABS computer unplugged. Even with the 4wd relay disconnected as well. I’ve been tracing the harness looking for a short to ground for the last few days.

I have the FSM and the factory wiring book as well. Tracing all of those circuits, I still can’t seem to find the fault.
I’m gonna keep digging though.
Another possibility would be behind the dash. Both CDL and ABS lamps are illuminated with a switch to ground. The CDL lamp passes through IH1 behind the glovebox.
 
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As a possibility, I forgot to install the reluctor rings on my front birfs when I rebuilt my axles 100K ago. My ABS light is on all the time because the system cannot operate because I don't have anything to sense in there.

Maybe the PO did that here as well and you're chasing something where you are assuming it has all its pieces in place, when they're not.

You can pull the ABS sensors and stick a finger in the hole to see if you can feel the reluctor rings.......
 
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Yeah it’s tripping me up. The abs light stays on even with the ABS computer unplugged. Even with the 4wd relay disconnected as well. I’ve been tracing the harness looking for a short to ground for the last few days.

I have the FSM and the factory wiring book as well. Tracing all of those circuits, I still can’t seem to find the fault.
I’m gonna keep digging though.

Remove the ABS computer again along with the ABS relay. The relay pulls the light to ground when it is de-energized through the data-link connector I believe. If the light is still on measure the resistance from ground to the light pin on the harness side of the ABS computer with it all still disconnected.
 
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Got it all figured out. I didn’t end up finding exactly what was wrong, but I ran my own circuit from the abs, and CDL light in the back of the instrument cluster, replacing the entire pink and black wire circuit from the abs computer, and basically eliminating the IH1 plug.

I just have it all barely connected, but confirmed it works perfectly.

I will post pics, just include case anyone has the same issue.
 

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