After searching the forums for an answer, and not finding one, I need some help. Has anyone here experienced the axle lock engage and disengage infrequently and without warning? I was rolling along the other day when I heard a grinding noise and then a loud THUNK that shook the front of my Carry. I noticed that the axle light on the dash was on. Then off. Then a few minute later, again the grinding noise and a THUNK. The axle light was going on, then off. I nursed it home at low speed while this weird axle lock engaged and released several more times. And no, I'm not hitting the switch on and off with my knee, I was careful to check for that. The next day, I disconnect the axle lock switch thinking this might keep the infrequent engaging from reoccurring, but nope, still did it again twice. Anyone have an idea what is causing this and the fix, or in the interim, how to disengage the front axle lock system until I can figure it out? I miss driving my mini!
Tool Man Tim, any luck? What your describing has happened to me before. A new Axle Lock switch, did not, do the trick for me. This thread, 1990 Carry DB 51T 4WD Shift Controller, gave me some understanding and a direction for troubleshooting. I hope it helps you. My plan is to replace all 4-wheel systems related vacuum hoses and then investigate that micro switch under center console.
I have the same problem as the OP. I haven't eliminated it yet, but I can work around it. If the Axle Lock light comes on when I first turn the key, I quickly turn the key off and then on again, and it usually goes out, and then I'm ok to go in 2wd. (If the light comes on while driving, I can perform the same maneuver by putting the clutch in so the truck idles.) If I don't notice it's on while driving, I get the same symptoms as the OP: Loud ticking from the dash and then a loud bang as it attempts to lock the front hubs at speed. The key-thing is a work-around, but I'm looking for a permanent solution.
I’m not certain of what you have going one. But this is how I would start trouble shooting. Somewhere something is opening or closing randomly. Generally this is caused by something loose, or a wire with the insulation worn through. Get a few piezo emitters, warning buzzers, etc. Any thing which makes a good noise when it get voltage to it, and wire them into the harness as a replacement for the vacuum swtiches/relays at the vacuum actuator. with the ignition on and the truck not running, switch 4wd on to make sure they make a noise loud enough to hear it. Then turn 4wd back off, and start jiggling wires, switches and connections. When the buzzer goes off, check out what ever you were wiggling when it went off. Or, if you’re searching for a justification to buy a fancy tool, get a fox and hound, and start chasing the wiring. I’m not sure if the system on the Carry’s is ground or hot controlled. But somewhere either in a switch or the control wiring you have an intermittent open or closed and that is trying to engage and disengage 4wd, as bumps in the road are wiggling things.
The Carry's system seems to be a typical 90's negative ground. I suspect a switch problem because when the switch is off (unlit) everything is fine. A problem a '95 Carry does enjoy is that there are two Axle Lock switches: One on the lower right-side dash and one that's paired with the 4wd lever between the front seats. I don't suspect a vacuum problem as the hubs are readily engaged when the switches are engaged. When the Axle Lock switch is lit (or the 4wd lever is engaged), I can hear the 4wd controller behind the dash activated. I suspect there's a problem with one or both of the switches, most likely the dash switch. It's Monsoon season here in southern Arizona right now, but if the weather clears for long enough, I figure it's time to break out my multi-meter and do some wire-chasing.
I have the same problem with my 91 DD51T. I removed the 4wd controller (above fuse block and behind the steering column), took it apart, and found a burned spot on the circuit board. I'm trying to attempt ahot wire solutin to this.
A ground short is a real possibility if the Axle Lock switch is ground-controlled like the headlight switch(es) are. I can't say for sure that the Axle Lock switches ARE ground controlled, but if the headlight switches are, it's likely other switches are as well. There is a second Axle Lock micro switch that is supposed to engage when the 4wd lever is engaged. On my truck, the 4wd lever doesn't engage either 4wd or the Axle Lock by itself, but when I get the Axle lock to engage at the dash switch, the 4wd will readily engage using the 4wd lever--and then everything works great. I just get the impression Suzuki made this more complicated than necessary. (I really miss the manual hubs on my old Samurai these days.)
Mike Fiesta (YouTube: "Maintenance Guide for Suzuki....") decided to bypass the sketchy electronics and (at 17:43) installs a physical vacuum switch for the axle lock. It's a solution I'm going to pursue, I think.
My bad. The video is by Mike Festiva. Mike could've gone into more detail in the video (e.g., where did he source the vacuum for the new manual switch?; how and how much of the existing system did he remove?), but I think Mike assumes we have more experience/skill than we frequently do have. Nevertheless, I really like his solution. It's elegant in its simplicity.
I've finished the Mike Festiva axle lock solution, and it works great. This fix will bypass the electronic 4wd module that tends to fail after 25+ years, providing a reliable way to engage the front hubs. Begin by removing the VSM and all its wiring and vacuum lines. But, when removing the wiring, be sure to leave the status switch wires intact (the wires with the white connector). 1. The new switch, a simple 3-way on/off vacuum switch sourced from Amazon, will be mounted on the center console. 2. Run one new vacuum line from the port between the two brass vents on the new switch to a vacuum line on the engine. I used the original source of vacuum to the VSM. 3. Run two additional lines from the other two ports on the new switch down to the front axle lock actuator (on top of the differential). (Note: You will need to slide small rubber vacuum line leads onto the metal diaphragm tubes so you can connect the harder, blue urethane tubing onto them. I sourced the adaptor pieces at ACE Hardware.) 4. Once all the lines are connected, check to see if you need to reverse the two vacuum lines exiting the switch so the axles lock when you pull up on the switch. That's all there is to it. Many thanks fo Mike Festiva for the original idea.
Just a note: If I had to do it again, I'd probably use rubber vacuum line like the original. That would preclude the extra hardware in Step #3 in that the rubber lines could connect directly to the actuator ports. I used poly because Mike did, and I had planned on replacing all the vacuum lines with poly eventually.
Thanks for the detailed write up. I just got my first kei truck a week ago (Suzuki Carry DB51T). The axle lock hasn't glitched out on me (yet), but I want to swap out my open differential for a locking one. I saw that exact video on YouTube and he also mentions that he used the vacuum hose method for activating his rear diff lock. He doesn't go into a lot of details in the video and I am a newbie mechanic so this certainly helps
Thanks for the write up! Definitely helps as Mike Festiva's video doesn't go too much into the details.
