4l80e temp gauge through OBD scanner?

[Duallylife]

I have a 1993 k3500 with a 4l80E, I'm looking to install a temp gauge, I know the best place is in the pan but I don't want to drop that right now as I just had a flush and it's a real pain to drop mine. I would also rather not deal with one in the cooler lines as I can never get those to work or stop leaking... I was in at a local shop I deal with for a "check up" on another vehicle and got talking to the guy about temp gauges and he told me the 4l80E's have a temp sensor built in (which they do) so just plug my OBD scanner in and use that as it would be easiest, but I can't find any OBD I scanners that are even digital let alone check stuff like that? All I can find is the ones you plug in with the little lights that flash. Does anybody know of a OBD I scanner I can use, and hopefully one that won't Break the bank.

 

[stutaeng]

Yes, as far as I know all 4L80e have a temperature sensor. I believe the computer somehow knows the temperature (and even throttle down power (or limp mode?) if it senses temperature is too high?), yet I don't know how one would go about outputting this information into a temperature guage of some sort.

I don't know if the Tech2 does transmission temperature. Those are as advanced as the snap-on stuff, for a lot cheaper. But I don't know if those read OBD-1 though. I think they are compatible with '92 to '13 models so may be worthwhile to look into those.

 

[df2x4]

But I don't know if those read OBD-1 though.

They do, or at least they're supposed to (I don't have any OBD1 vehicles so I haven't tested personally). They come with both OBD1 and OBD2 connectors and the software states they're compatible with '91-'13 GM vehicles.

 

[stutaeng]

Cool. Did you buy the clone?

 

[df2x4]

Yup, mine was around $350 on eBay.

 

[stutaeng]

The only thing I can think of is to look at the wiring diagrams and see if you can tap into the temperature sensor/sender circuit and compare the resistance to the resistance of the typical temperature senders used elsewhere on the engine. If so, it will be just a matter of connecting an aftermarket temp. guage to that wire. You'll probably have to get a new transmission wiring harness just to do this.

IIRC, the Haynes manual has some resistance vs temperature tables you can use to check engine temperature senders. I was messing with a sender once to see if it was working and heated with a heat gun while checking resistance. I have a spare 4L80e harness on my garage at the moment. I may just do that if I remember because I'm curious now...

 

[Schurkey]

I can't find any OBD I scanners that are even digital let alone check stuff like that? All I can find is the ones you plug in with the little lights that flash. Does anybody know of a OBD I scanner I can use, and hopefully one that won't Break the bank.

Those aren't scan tools. Those are consumer-grade GARBAGE.

You are going to LOVE what a real scan tool can do. One of these days, I'm gonna connect my tool to a GMT400, take some photos, and let folks know how easy diagnostics can be.

I damaged the scan tool I'd been using for ~20 years, so I bought a used one from eBay about a month or so ago. You do have to be careful to get one that includes the software and adapters/keys/connectors/ suitable for the vehicle you're working on; and has a recharger for the battery that will be mostly crapped-out.

There's heaps of professional-grade scan tools on eBay, craigslist, pawn shops, etc. Prices range from <$200 for old stuff, to "Very Expensive".

I bought a Snap-On Solus Pro with 8.2 domestic and Asian software, (usable with vehicles up to 2007) a bunch of Asian and a few domestic adapters (I already had all the Domestic adapters I need, from my previous scan tool) the recharger, a battery pack that not totally worthless, all in a bigass suitcase to store it in. $350, shipped to my door. ~$500--$600 is more common, but that generally gets you newer software, typically good for up to 2012, maybe 2016 vehicles.

My previous scan tool was a Snap-On MTG2500. They're ancient, but--in good condition--they do a fine job. The progression of Snappy scan tools was
MT2500, MTG2500, Solus, Solus Pro, Solus Ultra, Solus Edge, and the current version is Solus Legend. The newer the tool, and the newer the software, the more you're gonna pay. Support for the '2500s, Solus, and Solus Pro has already ended. Snap-On will do NOTHING for you if you have a problem, and you can't buy updated software, either. Solus Ultra support supposedly ends at the end of this year.

There are competing tools from other manufacturers, and there are software-plus-your-laptop-and-an-adapter-cable solutions; I've used NONE of them so I can't help you there.

 

[Duallylife]

I'm not sure what tool the guy I go to uses, but I have a Innova 3100 or something like that which I use for OBD2, not the most expensive but also not the cheapest and gets the job done.

Whatever he has he can plug into my OBD1 port and tell me most things just like OBD2, I brought him the truck in about 2 years ago because I thought I blew my fairly new trans because it would slam gears then randomly stick in one or not shift out, sometimes it would hunt. He got me to take him for a drive once he plugged his tool in (wish I had payed attention... Darn...) and he showed me It could show him everything, trans temp Engine coolant temp engine RPM trans input RPM oil temp what the TCM was set to shift at, (in tranny lingo) what the trans sensors were telling it to do, all the goodies. Turns out my 4wd shift rails got bent and when I shoved it in 4lo to crawle down a icy hill out of hunt camp with the trailer it smacked the electric shift module off the side, he was able to see the funky stuff the trans was sending itself and from knowledge of those trans tell me what it was before even crawling under.

I brought my sisters 05 trailblazer to him the other day because she lost second and OD and wanted to make sure it was the bands before digging into it for nothing, he told me with his scanner on the truck he could basically see anything, christ he could almost tell me what light bulbs were blown haha. He said his other scan tool he uses on mine is almost as good, it's just more dumbed down and raw data since it's OBD1.

When the trans went out in my truck about 5 years back it was reverse got very weak, couldn't back uphill while plowing, and if I had snow under me forget it. If memory serves me correct he diagnosed it with his reader by reading what the input shaft? Or flywheel? Maybe the torque converter? Was spinning at vs the output shaft, he said it's the sensors that tell the converter when to lock up, and there should only be a certain % of difference/ slippage and mine was way beyond so he knew it was clutches. Maybe he was bull sh*%ing? Either way he was right. It's crazy what OBD1 can actually tell you if you know how to read the data, I just want to know a temperature without having to drop my pan, create leaks or spend 3 paychecks and sell my arm to snap-on.

 

[Duallylife]

Doing some more research alot of guys say they put a sending unit in the pressure test port above the PRDNL switch, anybody have any experience with this? Some say it wont get an accurate reading, some say it may do some witch craft, most say it works fine, alot of them just say to be careful about the length of your sending unit because you can go to deep, they say measure your depth with something (Allen wrench or something) and compare it to your sending unit, or use that magnetic measuring crap on the end and gently thread it in and check how much is left.

Most recommend a shorter sending unit like this

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What do you guys think? Any objections? I don't see why not? I mean currently its just a bung in the side of the trans now, I'm basically just putting a shinier bung with a wire on the end in instead? Don't see what voodoo magic it could possibly do to the trans as long as it doesn't bottom out? To me it should also read fairly accurately I mean fluid obviously flows past it if it's a pressure testing port, and it's fluid that is flowing within the trans so it should be a fairly accurate temp I would think? Then again what do I know I'm just a shade tree mechanic haha.

 

[GoToGuy]

I have gathered alot of items to do my trans temp, oil temp, gauge pod soforth. I'm pretty sure that "Glowshift.com" has has a temp sender thats shorter also for smaller fluid galleries. At least last they advertised it specifically for confined, limited space applications. Good luck.