1996 gmc abs can't bleed

Hey, anyone know if snap on MODIS is supposed to be able to activate the ABS pump on 1996 Kelsey brakes? 1996 GMC 1/2 ton 4X4 Pickup. I read to use "tech I" tool. Also read "any decent scan tool"...
Can't find anyway to do it with my MODIS... (so much for it being decent, it's nothing but a headache 9 out of 10 times try to use it).
Had to replace rusted rear brake lines. Master resevior for the rear brakes got run dry. ABS hasn't worked for a long time and customer doesn't want to fix that. I can't force the pump to run by driving it because abs light is on for front wheel sensor (along with other codes) so it seems I got no way to bleed it out to get rear brakes working.
Anyone know of a way to force the pump to run??? Hot wire it??? Or what scan tools will give the option to run the pump?
THX
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OBDII? I know OBDI you can jump a pin on the ADL connector.
Cheers
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WOW! Got a reply! Thanks Martin! These NG's are so totally dead compared to years ago! Yeah, it's OBDII. No option for jumping on the DLC that I'm aware of. I was looking at wiring schematics and it looked pretty hopeless, but I think I'll look again with regard to the DLC.
I did learn that Snap On MODIS has the "automatic bleed" option added to later software. YEE HA, all I have to do is spend almost 1200 bucks to update. LOL, a little guy like me won't ever make enough with it to ever be worth all the updating expenses. This morning I can drive it 70 miles to another shop that has later version software (my brother's transmission shop), unless I can find someone local who can help me out. Anyone local to Concord, NH following this thread with MODIS version 9.2 or later?? LOL.
I'll update if I find another solution! IN2

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On 4/22/2010 5:53 AM, In2hoppn wrote:

Well, this might be a long shot, but my local Autozone lets me use their scanner, for free. Compared to the one I used to own (and the separate programmer), it is light years ahead in straight functionality and speed.
The catch? It probably does not have the ABS feature you seek, but is worth a shot if it does do as you need, and they'll let you perform the task in their parking lot.
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Hey, thanks so much! Next time I'm at the Zone, I'll see what they have, just for the heck of it... (I got friends there...) : ) But, it's finally all bleed and on it's way! A shop down the road was nice enough to activate it for me. Snap on Solux (and fairly up to date I imagine) did the trick. BUT, it wouldn't allow that function without codes cleared, and the bad front left wheel sensor would set the code right back in. Had to go back home, rig up a resistor to simulate the wheel sensor being good. Went back down there with that, and my pressure bleeder attached and bleed bottle... LOL, they treated me pretty well and it's finally done.
Definitely no way of getting the air out of that unit any other way! Thanks all!

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On 4/22/2010 5:08 PM, In2hoppn wrote:

Good to hear. Most of the shops will help you out if you are a DIYer, there might be a time when you really need them...
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You shouldn't need a scan tool to bleed the rear brakes unless the ABS actually activated while the master cylinder was dry allowing air into the ABS modulator. Under normal circumstances, the ABS valves are closed, air can not get into the system unless the valves are commanded open like during an ABS event or via a capable scan tool. If air got in because of leaking valves, you have other problems. If air got in and the valves are -not- leaking and you still can't get a firm pedal, you've got other problems.
As for using your Modis more effectively, Snap-On has plenty of free online training. The worst time to learn a tool is when you're under the gun trying to fix a vehicle.
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wrote:

I have to disagree with this based on this vehicle and one other in the past. My experience is that if the master runs out, air gets trapped in the abs. The vehicle in the past would not bleed the air out, just fluid by the quart... until activating the pump (by driving and braking). Then all was fine. Same for this vehicle after I found someone with the tool to activate it. I know this one didn't activate with master dry because there was no fuse in it. As far as I know (or can imagine) the truck in the past wouldn't have activated because the brake warning light (red) had come on first when line blew and that disables the abs. Now if air trapped under these conditions indicates another problem that is in itself not a problem before or after... well that may be because I know very little about the abs unit itself. My understanding is that there was a variety of different abs system during these years. Perhaps what you state applies to a different system?

Now THAT I did NOT know. FREE online training?? Any vehicle specific stuff or just using the MODIS in general??? Although just the latter will be worth looking into! I'm writing myself a sticky note right now to look into that. My customer base is NOT new cars so really for me the MODIS has been overkill (but I did buy it used). And of course the "older cars" have gone from the 80's to the 90's to now all the 00's so I really do need to get using it much more. You are absolutely right. There has been no good time for me to really learn the MODIS. My first frustration with it was trying to "make movie" like on the brick. Doesn't do that the same way at all. I still prefer to grab my brick. Especially for on the road because usually the vehicle I'm working on is worth less than what I paid for the MODIS so the brick just feels safer : ). LOL. The place I went to that activated the abs for me used a SOLUS. First I've seen that in action. Looks to me like a MODIS minus the Vantage part??? The MODIS does seem like way to much to dig out just to pull codes. My impression is many have been shying away from them? Last I knew there were plenty of used ones on ebay... at least back when I bought mine... : )
Thanks much! I appreciate your input and will look into the online training...
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Being in Wisconsin, I assure you that I have replaced many-many rusted out brake lines on GM and other brands of vehicles with ABS brake systems. I have never needed a scan tool to bleed the brakes unless there was another concern that allowed air into the ABS modulator.

Air can not get into the ABS modulator UNLESS the valves are either leaking or were cycled such as would happen if the ABS is activated.

Then there was probably a chunk of crap lodged in one of the valves and it flushed past the valve when you used the scan tool.

There were/are a variety of systems out there but they all operate essentially the same.

No vehicle specific stuff, tool usage only.

Back when the Modis came out, I coined the phrase "Golden Handcuffs."
I never saw the advantage to the tool, I DID see the disadvantage to having three tools bundled together, from the update point, the usage point and the repair point. More cost to update, tool tied to one car when needed on another for a different function and when it breaks and needs to be sent in for repair, you're out all three tools.

But on the other hand, you can print more easily/cheaper, you can build a database of known good/bad data, you can interface with a PC for full screen view, you can connect a larger monitor.

Solus or Solus Pro? You don't want a Solus, you DO want a Solus Pro. Much better unit.

Absolutely! But why not use the rest of the tools capability? The labscope and the graphing multi-meter?

True that. I've shied away for 10 years now. I've used them at other shops so I am familiar with the tool.

http://www1.snapon.com/ForumsTraining.nws
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Yeah, or if the seals are just crappy and still don't seal... is that a problem that otherwise, well, doesn't cause a problem???

Have never printed with either. Just jot down codes, make quick notes... guess that's because I couldn't print from the brick but I see (via some of that online training you recommended) that I can probably print using my inkjet!!!!!

It may have been the Pro. All I know it the screen/menu was similar to my MODIS except of course a much smaller unit (and had the needed option to activate abs). What's the difference, Solus vs. Solus Pro?? ... basically? ... in a nut shell? ...or all the detail?? I appreciate your very informative posts!!!!!!

So far, haven't needed to use labscope yet. And of course I always grab the old Vantage meter, if my 2 dollar short lead cheapy meter hasn't already done the trick.

Yup, that's were I've been. I gotta say, it's pretty slow and annoying! 1st, is each slide has like a 15 second silent beginning (OK, haven't timed it, but it's SLOW). Then theres all the slow motion, detailed to the point of bragging, instruction of the very basic tool operation. Wish there was a way to increase the play speed : )
The battery charging has always annoyed me. First, because it's always dead when I pull the tool out. Then, because it has to be ON to charge battery, and it doesn't shut down after... Apparently, if you plug it in but leave it powered off, it is NOT charging the battery at all? Someone told me to pull the battery out after charging in if it's going to be sitting unused for long. I'm trying that...
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