impossible Cruise control module diagnosis/ b4 vr6

[waybux]

My cruise control doesn't work nor is there any presence of a dash indicator light when I turn on the switch.

Per Bentley: for manual transmission
1) test fuse- ok
12 pin test at cruise control module:
test voltage- pins 9 and ground = expect 12v = ok
ECU grounds- pins 9 &4; 9 &12 (ignition on, cruise on) = expect 12v = ok
cruise cont. switch- pins 8 & 4(push set button) = expect 12v =ok
cruise cont switch- pins 5 & 4(push resume button) = expect 12v =ok
cruise cont clutch
brake pedal- pins 3 & 9 (depress clutch, then brake) = 12v; 0v when depress =ok
vss pins 7 & 4 (lift front of car, spin wheel) = expect cycle high/low
voltage =ok

jumper: (9 & 11) + (1 & 4) + (2 & 4) with key on/ cruise on= cruise vacuum pump runs, accel. pedal goes to floor. Stays at floor. no leaks, no problems.

Per Bentley, replace module.

I replaced with 3 different used modules. 2 are from jetta's with Identical markings. 1 from b4 vr6 automatic. Test drove each one. No change in function.

Is it possible that I got 3 additional bad modules plus mine?

I thought that maybe the internal relay was bad on the circuit board. Researched remedy on vw vortex.

Followed the instructions on this link to remove relay and solder in an aftermarket relay externally. made no difference. http://forums.vwvortex.com/showthread.php?3434133

any help out there ???

[SilentDawn]

I'd say YES, you got 3 bad modules. I have about 20 modules in my shed that don't work and need repaired. I FINALLY ended up finding one that worked and have just been using that one.

What needs to happen is all of the varnish/wax stripped off the contact side of the board and EVERY solder point heated with an iron and re-flowed. I think some people have had good results with just heating the solder through the varnish. As long as you add in good electrical solder, that should work. The hardest part is stripping the varnish off.

[waybux]

So, just to make sure, if I go around to every junk yard and keep trying different modules, they should all fit from those years right? IE. from corresponding years of jetta, cabrio, etc as long as the markings are similar?

Or what would be a solvent that might remove the varnish? Xylol? Acetone? Because I might just try doing that. I could use the solder experience.

Last, is there a dash light that should light up when cruise is activated?

Thanks again for your help. I always appreciate it.

[SilentDawn]

I used MEK (Methyl ethyl ketone) to loosen it up. But...

Its VERY bad for you...And I think its illegal to sell now. I think you can pick up MIBK (Methyl isobutyl ketone), which is a "substitute" Also VERY bad for you. Wear thick SOLVENT gloves. It eats right through the nitrile gloves.

Also MEK cut through the epoxy resin covering the solder traces...Not good. But if you apply an insulating varnish after you're done, it should be fine. Not sure what MIBK will do.

Lacquer thinner might do the trick also, but I'm not sure.

No matter what solvent you use...Its a pain in the butt.

[waybux]

ok, so I will get a couple different solvents and experiment with one of the 4 modules that I have.

Then I go through and reflow all of the contacts on the board and see what happens. It will be nice to learn how to do this type of repair. It seems as if one of the only thing that has failed on my b4 are different modules.

I think maybe I will get a 45w or 60w cheap iron to try the other method you metioned about burning through the varnish to the contacts. you said I would have to flow new solder. What do you mean by this? That after burning through the varnish to the contact point, then simply flow a little extra new solder on that spot? Or is there a step in there that I missed. Sorry if that sounded like a dumb question.

Hey thanks again for your guidance.

[SilentDawn]

That after burning through the varnish to the contact point, then simply flow a little extra new solder on that spot?

Yeah. Use rosin cored solder, the thinner solder flows better for this kind of work. I'd get a soldering iron with an adjustable temperature. Sears sells a Weller solder station for like 40 bucks that works fine.

Make sure you go back after its all done and scrub the solder joints with isopropyl alcohol and a toothbrush or something to get the flux from the solder cleaned off.

[waybux]

I got off all of the varnish with some toulene and xylol. I used a soft brass brush to light scrub while it was saturated. It looks as if it did a pretty good job. I did make a few scractches in the green printed board. I took a few pics of them. The pen in right next to the scratches. Do you think these will pose a problem.

[SilentDawn]

Nope. That scratch will be just fine. When you're done I'd cover it with clear nail polish...Unless you happen to have some type of conformal coating to cover it back up to prevent corrosion.

Start soldering away. Hit EVERY solder point.

Not sure how knowledgeable on soldering you are, but you want to get a smaller tip (Pencil tip or small chisel tip). You also need to "tin" the tip of the iron and keep it clean on a damp sponge when the solder starts to burn on the tip.

You also want to add just a touch of solder (That's why you want thin solder) to each joint when re-flowing. That's the whole problem with these boards is lack of solder and "cold" joints and over time the solder joint gets a microscopic crack.

Plenty of good video's on youtube if you'd like some more info.

[koolkevin43]

Personally, I'd recommend using de-soldering braid and re-doing each joint. I've fixed multiple little PCBs (guitar pedals, Key fobs, computer parts, etc.) and if I just re-heat the joint and flow more, it only works about 75% of the time. Removing the old solder and giving it fresh clean new joints gives me peace of mind as well. These things tend to be very tedious so I don't want to come back a second or third time.

[waybux]

Nope. That scratch will be just fine. When you're done I'd cover it with clear nail polish...Unless you happen to have some type of conformal coating to cover it back up to prevent corrosion.

Start soldering away. Hit EVERY solder point.

Not sure how knowledgeable on soldering you are, but you want to get a smaller tip (Pencil tip or small chisel tip). You also need to "tin" the tip of the iron and keep it clean on a damp sponge when the solder starts to burn on the tip.

You also want to add just a touch of solder (That's why you want thin solder) to each joint when re-flowing. That's the whole problem with these boards is lack of solder and "cold" joints and over time the solder joint gets a microscopic crack.

Plenty of good video's on youtube if you'd like some more info.

Thanks for the info I will check out youtube for a crash course. I called sears by me, they don't carry the weller base that you told me about. I gonna try Frys (local electronic store) this weekend. I keep you posted.

Thanks again

[waybux]

Personally, I'd recommend using de-soldering braid and re-doing each joint. I've fixed multiple little PCBs (guitar pedals, Key fobs, computer parts, etc.) and if I just re-heat the joint and flow more, it only works about 75% of the time. Removing the old solder and giving it fresh clean new joints gives me peace of mind as well. These things tend to be very tedious so I don't want to come back a second or third time.

I was thinking of trying to desolder and then resolder some of the things that I read may be more prone to cracking, i.e. capacitors. I heard that they heat up and expand, then cool down and shrink; which cause them to break their solder points.

Thanks for the input.

[SilentDawn]

Thanks for the info I will check out youtube for a crash course. I called sears by me, they don't carry the weller base that you told me about. I gonna try Frys (local electronic store) this weekend. I keep you posted.

Thanks again

Hmm, they've gone up in price (Like everything else)

http://www.sears.com/weller-new-wlc1...3&blockType=G3

I would normally recommend that you desolder...However, that does introduce much more heat, especially if you don't get the solder off and reapplied in a quick, efficient manner. Components can take quite a bit of heat, but the risk of damage IS there. De-soldering the joint before flowing in new solder also GREATLY reduces the risk of bridging solder joints that aren't supposed to be. But honestly...I've fixed and sold maybe 6 of these that I just flowed in new solder without removing the old solder...And I've had no complaints.

If you go that route, maybe get a little plastic solder sucker. Sometimes thats quicker than braid...Sometimes you need both. Solder suckers work pretty good for through-hole boards like these. Not so good for SMD (Surface mount, tiny components.) Also, wear safety glasses...molten solder in your eye is a very bad day.

[waybux]

ok I will just start with re-flowing the solder and adding a little bit of new solder to the thin spots.

originally, after I saw that website that I linked earlier, it said that the relay is what might be bad on the board. It gave instructions for removing, desoldering the relay and soldering in new wires so I can install an external aftermarket relay. I did all this before I spoke with you. Should I leave those wires in or should I reinstall in the original relay.

[SilentDawn]

You should be able to leave your new relay in.

[waybux]

Question regarding cooling fans. When I bought the car the fans would always make a squeal, that was especially noticeable when I shut the car off and the cooling fan would go into after run mode. I always thought that maybe it was the bearing going out inside the electric fan. The exterior of the fan appeared to be normal.

The other day when the a/c was on max and it was 103deg here in Sacramento, all of the sudden I felt the entire car have a weird vibration. When I inspected under the hood, the fan was extremely faster than I have ever seen before. I assume this must be the high speed out of the three speeds. This made me wonder why I never felt before. After inspecting in between the fans, shroud and radiator I saw a plastic piece broken.

I took of the front end of the car to get to the radiator (fun, lot of work) and pulled out the plastic pieces. It appears that the ring that surrounds the fans had broken and been rubbing the belt that goes from the main fan to the auxiliary. Then it finally came loose and now the fans are running triple speeds.

My Question: The plastic piece according to the bentley is a guide ring (#10 on diagram). Because it was busted I had to remove put everything back together. Do I need this ring? Everything looks to be ok and operating just a lot of vibration. I not sure if vibration is normal when fans are running without restriction or if mine have developed and internal balance issue (i.e. bearing or wear from hitting the broken ring for so long).




I haven't got a chance to continue to work on the modules for the cruise but I will let you know as soon as I make some progress.

[SilentDawn]

Generally the fans are pretty quiet. Hardly noticeable at all unless they are running on high. Then its only normal fan noise. No vibration, no squeaking.

Does the belt have a nick or chunk missing? Maybe that would be causing vibrations?

If not, I'd say you've got a blade warped or out of balance.

Being out of balance will just make the fan bearings fail sooner.

I'm not sure exactly what the two rings do. Likely to help direct airflow and to keep the blades in alignment and such when struck with small debris.