Replacement 12v test light for OTC 3633

[MikeH]

I wanted to buy a better test light and was going to get the one that scannerdanner seems to recommend, the OTC 3633, but it Is out of stock everywhere I looked. Indeed, OTC tells me that it is “obsolete without replacement.”

I don’t quite get why it wouldn’t be replaced. Anyway, I think the closest replacement is the 3636, main difference being the lack of the needlepoint tip of the 3633. I would like that, but can live without it. Mainly I want incandescent, and better build quality than the Harbor freight model. Is 3636 the way to go? Another OTC model? Something else altogether?

OTC 3636

 

[Steve_P]

I have the 3633; the box description is "mini coil cord circuit tester"
the 3636 description (same box) is "heavy-duty coil cord circuit tester"

Looking at the pic of the 3636, the red cord and the body of the tester looks the same to me. The 3633 has a short tip with threads like some multimeter leads where you can thread on accessories like an alligator clip; the 3636 looks to have the standard long probe tip. So, like you said, the 3636 looks to be the same other than the tip differences.

As long as you can deal without the threaded tip that the 3633 has, they look otherwise the same to me. The 3633 has good build quality and I'd assume the 3636 would be the same.

The 3633 is ~0.5A.

 

[MikeH]

Thanks. Does anyone know if there’s a good quality alternative that *does* have the threaded fine point?

 

[Wrench97]

I use the grinder to sharpen the tip.

The 3636 is a LED lamp.

I currently have a 3634 longer cord sometimes useful sometimes in the way> https://www.amazon.com/OTC-3634-Heavy-Duty-Straight-Circuit/dp/B002YKHCOQ/?tag=atomicindus08-20

 

[2ndGearRubber]

I have the 3633; the box description is "mini coil cord circuit tester"
the 3636 description (same box) is "heavy-duty coil cord circuit tester"

Looking at the pic of the 3636, the red cord and the body of the tester looks the same to me. The 3633 has a short tip with threads like some multimeter leads where you can thread on accessories like an alligator clip; the 3636 looks to have the standard long probe tip. So, like you said, the 3636 looks to be the same other than the tip differences.

As long as you can deal without the threaded tip that the 3633 has, they look otherwise the same to me. The 3633 has good build quality and I'd assume the 3636 would be the same.

The 3633 is ~0.5A.

It's like 300ma. I LOVE that little test light, I hope they bring back something very similar. I think I keep a spare here at the house in addition to my 10yo unit at work. Maybe I'll be a little more careful with it knowing it's discontinued. The tool truck guys tell me most people want LED units now. IDK why - it's all the downsides of a meter, with none of the positives.


The 3636 looks like an incandescent model per this listing - https://www.amazon.com/OTC-3636-Heavy-Duty-Circuit-Tester/dp/B002YKFA0O?tag=atomicindus08-20


That sort of OTC test lamp, with the small "fuse style" replaceable bulb is what SD recommends. You can stick that sort of test light into basically any circuit without fear, and it works as an actual load to test a circuit. I used that 3633, and a lab scope, to diagnose an open circuit injector today. Fed in a 300ma current to the injector control wire via the exposed portion of the backprobe on the scope. Labscope shows the constant 12v feed, and the driver in the PCM pulling the B+ to ground in an attempt to cycle the injector. Power feed from the relay was good, injector open circuit, PCM good. Sell an injector.

While my 3633 has a threaded tip, I almost never use it. I either connect it to a backprobe with my hand like the above example, or the test lead it's in series with will have an alligator on the end to hold the test lamp tip.

 

[Steve_P]

It's like 300ma. I LOVE that little test light, I hope they bring back something very similar. I think I keep a spare here at the house in addition to my 10yo unit at work. Maybe I'll be a little more careful with it knowing it's discontinued. The tool truck guys tell me most people want LED units now. IDK why - it's all the downsides of a meter, with none of the positives.


The 3636 looks like an incandescent model per this listing - https://www.amazon.com/OTC-3636-Heavy-Duty-Circuit-Tester/dp/B002YKFA0O?tag=atomicindus08-20


That sort of OTC test lamp, with the small "fuse style" replaceable bulb is what SD recommends. You can stick that sort of test light into basically any circuit without fear, and it works as an actual load to test a circuit. I used that 3633, and a lab scope, to diagnose an open circuit injector today. Fed in a 300ma current to the injector control wire via the exposed portion of the backprobe on the scope. Labscope shows the constant 12v feed, and the driver in the PCM pulling the B+ to ground in an attempt to cycle the injector. Power feed from the relay was good, injector open circuit, PCM good. Sell an injector.

While my 3633 has a threaded tip, I almost never use it. I either connect it to a backprobe with my hand like the above example, or the test lead it's in series with will have an alligator on the end to hold the test lamp tip.

Like you said, I'm not sure why you'd want an LED test light. Because you can just use a DMM, which everyone already has, to reach the same possibly erroneous conclusion.

I looked on my 3633 and I labeled it 300-600 mA; so, I guess I was getting fluctuating readings when I tested it.

Yeah, I've never used the threaded tip on mine. But IIRC I did replace the threaded alligator clip it came with with a good one as a just in case.

Who is SD?

 

[2ndGearRubber]

Like you said, I'm not sure why you'd want an LED test light. Because you can just use a DMM, which everyone already has, to reach the same possibly erroneous conclusion.

I looked on my 3633 and I labeled it 300-600 mA; so, I guess I was getting fluctuating readings when I tested it.

Yeah, I've never used the threaded tip on mine. But IIRC I did replace the threaded alligator clip it came with with a good one as a just in case.

Who is SD?

Scanner Danner, youtube channel.. Diagnostician and teacher of automotive electrical. He's worth the watch, check it out.

I thought I had ~300ma across a battery via an amp clamp, but I could be mistaken. Also 12v will have a different output than 14v with the car charging. A 194/168 bulb is about 250ma, a 3157 is ~2 amps, and a headlamp bulb around 4.5 amps.

I think the point is that even at 500ma, you can stick that basically anywhere with impunity and have no fear as to damaging something.

 

[Steve_P]

Scanner Danner, youtube channel.. Diagnostician and teacher of automotive electrical. He's worth the watch, check it out.

I thought I had ~300ma across a battery via an amp clamp, but I could be mistaken. Also 12v will have a different output than 14v with the car charging. A 194/168 bulb is about 250ma, a 3157 is ~2 amps, and a headlamp bulb around 4.5 amps.

I think the point is that even at 500ma, you can stick that basically anywhere with impunity and have no fear as to damaging something.

I honestly don't remember how I came up with my current rating- maybe just measuring a fluctuating resistance and then assuming a variable voltage range with the car on and off. But yes, I don't think it matters if it's in the general ~300-600mA range. Which it certainly is.

Ok, I have heard of Scanner Danner. And maybe I watched a video of his a few years ago and bought this tester before it was discontinued!!!! Lucky me

I have a Fluke amp clamp so I'll try to check it out for a second opinion. I know for sure that I didn't use the amp clamp to come up with my initial value

 

[Wrench97]

It's like 300ma. I LOVE that little test light, I hope they bring back something very similar. I think I keep a spare here at the house in addition to my 10yo unit at work. Maybe I'll be a little more careful with it knowing it's discontinued. The tool truck guys tell me most people want LED units now. IDK why - it's all the downsides of a meter, with none of the positives.


The 3636 looks like an incandescent model per this listing - https://www.amazon.com/OTC-3636-Heavy-Duty-Circuit-Tester/dp/B002YKFA0O?tag=atomicindus08-20


That sort of OTC test lamp, with the small "fuse style" replaceable bulb is what SD recommends. You can stick that sort of test light into basically any circuit without fear, and it works as an actual load to test a circuit. I used that 3633, and a lab scope, to diagnose an open circuit injector today. Fed in a 300ma current to the injector control wire via the exposed portion of the backprobe on the scope. Labscope shows the constant 12v feed, and the driver in the PCM pulling the B+ to ground in an attempt to cycle the injector. Power feed from the relay was good, injector open circuit, PCM good. Sell an injector.

While my 3633 has a threaded tip, I almost never use it. I either connect it to a backprobe with my hand like the above example, or the test lead it's in series with will have an alligator on the end to hold the test lamp tip.

Interesting the Zoro site claims red/green LED> https://www.zoro.com/otc-circuit-te...81u7dvSWyCdpgFZzPCMaAv22EALw_wcB&gclsrc=aw.ds
Are the bulbs interchangeable?

 

[Steve_P]

Ok, so for the first time I used the threaded tip on the OTC test light, got out a banana plug and threaded it on, got out a big clamp for a battery terminal and plugged that in. Got out the 87V, the amp clamp, hooked it up and turned on the meter.... and the battery was dead in my 87V

 

[MikeH]

Interesting the Zoro site claims red/green LED> https://www.zoro.com/otc-circuit-tester-612v-12-ft-3636/i/G2016071/?utm_source=google&utm_medium=surfaces&utm_campaign=shopping feed&utm_content=free google shopping clicks&campaignid=19976937521&productid=G2016071&v=&gad_source=1&gclid=Cj0KCQiAkeSsBhDUARIsAK3tiefI6pcU2FVD-AIGbi2155OHjBpaGWmSvD8u81u7dvSWyCdpgFZzPCMaAv22EALw_wcB&gclsrc=aw.ds
Are the bulbs interchangeable?

I’m pretty sure they are describing the 3633 (which is discontinued) and you linked the 3636.
Which I’m now leaning against since it is LED.

 

[2ndGearRubber]

Interesting the Zoro site claims red/green LED> https://www.zoro.com/otc-circuit-tester-612v-12-ft-3636/i/G2016071/?utm_source=google&utm_medium=surfaces&utm_campaign=shopping feed&utm_content=free google shopping clicks&campaignid=19976937521&productid=G2016071&v=&gad_source=1&gclid=Cj0KCQiAkeSsBhDUARIsAK3tiefI6pcU2FVD-AIGbi2155OHjBpaGWmSvD8u81u7dvSWyCdpgFZzPCMaAv22EALw_wcB&gclsrc=aw.ds
Are the bulbs interchangeable?

Heavy-Duty, Coil Cord Circuit Tester | OTC Tools

otctools.com

3636 looks like it uses the same bulbs as my mini 3633. OTC will sell you a 10 pack.

 

[Steve_P]

I’m pretty sure they are describing the 3633 (which is discontinued) and you linked the 3636.
Which I’m now leaning against since it is LED.

Unless the LED test lights have a resistor built into them to raise the necessary current to 300+ mA, I personally don't see the purpose versus just using a DMM. Because you are just fooling yourself if you have a low current only situation with either. You'd be much better off with a set of homemade test lamps using taillamp sockets and bulbs. There was a thread about that a few months ago here....

 

[KnurledNut]

I picked up the Lisle 24550 recently.
It has a thin tapered probe with a very sharp needle point, draws less than 21 mA@12v, operating range of 3-28 volts - safely works on 24v systems, and indicates polarity with red and green lights.

 

[richfinn]

This accessory works well with the OTC 3633, so you can attach any 4mm probe

I use it with my Pomona piercing probes/backprobes/power probe attachments

WTS-4TB-001 Threaded 4mm Banana Plug Adapter | Warwick Test Supplies

Threaded 4mm Banana Plug Adapter designed to convert a threaded OTC 3266 or other OEM automotive test light circuit tester or threaded test probes to a 4mm Banana Plug.

warwickts.com

 

[Wrench97]

I’m pretty sure they are describing the 3633 (which is discontinued) and you linked the 3636.
Which I’m now leaning against since it is LED.

I think the Zoro site is wrong in the description every other site I've looked at does not say LED.

 

[MikeH]

It finally struck me (I’m slow sometimes) if the 3636 and 3633 use the same size bulbs, even if the 3636 IS led, I’d I put an incandescent bulb in, it becomes what I want (minus the needle point and threads). Right? Is there any circuitry in the device itself, or is it just straight wired?
Same would be true of the Lisle linked above, if it has replaceable bulbs, I suppose.

 

[Wrench97]

Incandescents are straight wired.

 

[stonesfan68]

This accessory works well with the OTC 3633, so you can attach any 4mm probe

I use it with my Pomona piercing probes/backprobes/power probe attachments

WTS-4TB-001 Threaded 4mm Banana Plug Adapter | Warwick Test Supplies

Threaded 4mm Banana Plug Adapter designed to convert a threaded OTC 3266 or other OEM automotive test light circuit tester or threaded test probes to a 4mm Banana Plug.

warwickts.com

According to the description on this site then the OEMTools 25936, and the Actron CP7841 have a threaded tip much like the OTC. It wouldn't surprise me if both tools were made by OTC.

 

[billford]

I find led test lights next to useless for checking power. For checking grounds they are ok.

If checking for power, I always use a testlight with a domelight bulb in it. They draw about 1 amp.
If the test light is bright, the power is more than likely ok. If its dim, the circuit is more than likely bad. However, there are exceptions to this. Experience helps.

 

[N8sToolz]

I bought up a bunch of tool aid 27000. They have been pretty reliable to me over the years, minus me losing them.

250mA draw and pretty short money to buy.

 

[Steve_P]

According to the description on this site then the OEMTools 25936, and the Actron CP7841 have a threaded tip much like the OTC. It wouldn't surprise me if both tools were made by OTC.

I doubt OTC actually makes this. In fact, I doubt that there is an actual OTC plant in Asia that makes the stuff they import- which is probably 99% of their current catalog. My point is that AFAIK OTC contracts with overseas vendors for most of the stuff they sell. Which is fine, I have a lot of OTC imported pullers / slide hammers and they're good.

Anyway.... this does look like the OTC 3633 externally. But it's not the same internally. Maybe you can buy the 3633 bulb and swap it in? The bulb is different in the 3633 and the spring is on the other side. This one may be an LED?

edit- I went thru the pics on Amazon reviews, and one shows it drawing it 73mA. It's not the same as the 3633, and may be an LED.

 

[Buster21]

3633 is smaller but has a sharper tip and is threaded. Both use incandescent fuse style bulbs.

 

[Buster21]

Craftsman and Actron rebranded them. There are some on eBay under the craftsman brand #21012 and Actron CP7841

 

[Omnirod]

I wanted to buy a better test light and was going to get the one that scannerdanner seems to recommend, the OTC 3633, but it Is out of stock everywhere I looked. Indeed, OTC tells me that it is “obsolete without replacement.”

I don’t quite get why it wouldn’t be replaced. Anyway, I think the closest replacement is the 3636, main difference being the lack of the needlepoint tip of the 3633. I would like that, but can live without it. Mainly I want incandescent, and better build quality than the Harbor freight model. Is 3636 the way to go? Another OTC model? Something else altogether?

OTC 3636

That is nuts...by far my favorite test light. Good thing I bought three of them.

 

[Omnirod]

I honestly don't remember how I came up with my current rating- maybe just measuring a fluctuating resistance and then assuming a variable voltage range with the car on and off. But yes, I don't think it matters if it's in the general ~300-600mA range. Which it certainly is.

Ok, I have heard of Scanner Danner. And maybe I watched a video of his a few years ago and bought this tester before it was discontinued!!!! Lucky me

I have a Fluke amp clamp so I'll try to check it out for a second opinion. I know for sure that I didn't use the amp clamp to come up with my initial value

Mine measured at 180 or so milliamps.

 

[Steve_P]

Mine measured at 180 or so milliamps.

I've since checked mine "the real way", with a meter in series, on a 12.2V battery and I got 150 mA. My original assessment must've been just by measuring resistance and doing math.

 

[Omnirod]

I just bought a brand new 3633 today…

 

[WWheeler]

I wanted to buy a better test light and was going to get the one that scannerdanner seems to recommend, the OTC 3633, but it Is out of stock everywhere I looked. Indeed, OTC tells me that it is “obsolete without replacement.” [...]

OP's post is more than 6 months old, but just as an FYI the 3633 has been back in stock for a while now.

JBTools

OTC 3633 Mini Circuit Tester

Buy OTC 3633 Mini Circuit Tester with an everyday low price and free shipping!

www.jbtools.com

Zoro Tools on ebay:

Pardon Our Interruption...

Amazon:

Amazon.com

 

[MadeFromMetal]

Yeah the OTC 3633 and OTC 3636 are both incandescent and use the same bulb type the red filmed incandescent bulb "OTC3633-10" is like $16 for a 10 pack on Amazon.

I love the 3633 it's crazy good quality. If you want a lower grade quality version you can get the OEMTools mini coiled circuit tester but it comes with LED bulb in it that you can swap for the OTC one.

LED circuit testers are pretty much useless in 99% of circuit troubleshooting because they don't load the circuit. The Red/Green indicators on LED circuit testers are just tools to get you in trouble and you should never rely upon those LED polarity lights. There are far to many circuit issues that can give false +/- readings on the wrong wires. Best bet is to always use a wiring diagram (Mitchell if you can afford and Mitchell-DIY for $20/month or $39/year for a single vehicle or $200/month for pro version no vehicle limit) that way you know exactly what wire color is and what you're probing. That's the best course of action since test lights are essentially jumpers and as long as you know what you're looking at you won't dry anything and will use your O-Scope on 2.5V/5V refsig or control wires and computer power wires that there's the potential of overloading the circuit that doesn't have transistor or diode protection.
But for 99% if electrical diagnostics a incandescent test light is your best friend and honestly all you need to find most circuit faults.
You can get some modules drivers with 1-4A taillight/circuit testers but the OTC 3633 only draws 158mA-250mA on 13.9V depending on the bulb of choice and that's not gonna fry anything I've ever worked on.

 

[Shehzada]

Craftsman and Actron rebranded them. There are some on eBay under the craftsman brand #21012 and Actron CP7841

Craftsman and Actron rebranded them. There are some on eBay under the craftsman brand #21012 and Actron CP7841

I just bought the Actron one and it indeed is identical with the exception of the much shorter coiled cord and the absence of the alligator screw-on tip.