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I have been trying to fix my cruise control for some time now. I picked up 7, yes 7 different cruise control boxes, 5GA 004 397-14, from junkyards trying to find a good one. I had one that would work when it was warm. The rest would not.
Then I found an Audi site that talked about the same issue for a 5GA 004 397-16 board. They look the identical. Seems that one of the guys there found the bad solder joints on the boards. Here is the link to the posting. Definitive solution to repair cruise control module 5GA 004 397-16 - AudiWorld Forums
Here are the pictures showing where to re-solder. The questionable joints are C7, C9, and C11 capacitors.

After a little solder work, I now have 6 functional cruise modules. I found a few other questionable joints that i soldered also. Make sure you scrape off the red coating before you try to solder... :K:
If you have checked the rest of your cruise system and it checks out, give this a try!

2 Posts
MKIII Cruise control not work - how to fix

How to fix a bad cruise control module. For Volkswagen 5GA 004 397-11, for Volkswagen 1H0 907 305.

READ here to diagnos and repair your module! Sorry i don't know how to add images to my post

Like most MKIII owners my cruise control was pretty much decoration on the steering column, but not anymore.
The car passes the Bentley test and passed every time. Examined the circuit boards under magnifying glasses looking for bad solder joints, nothing everything was good.

google "fix volkswagen cruise module"

1. Perform the Bentley test
“Remove trim cover over relay panel. Unclip relay/fuse panel, and move it out of the way. Pull the door chime relay so it doesn't annoy the hell out of you. Stick your head back there and shine a line back up from the underside toward the front of the dash (almost right behind the headlight switch). You'll see a white and silver box next to each other. The silver one is the cruise ECU. Pull the 12 pin plug from the back.
To do the test, simply cut some little pieces of thin solid wire (utility wire found at any hardware store) and wrapped them around the ends of the probes on my multimeter so that I could stick them into the harness slots and let the probes hang.

Here's the reader's digest condensed version of the tests. Probes on pin 9 and ground. Turn on ignition and cruise control on stalk. Should see 12V when on. 0 when off. (Tests voltage supply)
Probes on pins 9 and 4 (9 and 12 on some cars). Ignition on, cruise on.
Should see 12V when on, 0 when off. (Tests ECU ground)
Probes on pins 8 and 4. Ignition on, cruise on, push and hold Set button.
Should see 12V when Set pressed, 0 when released (tests set button)
Probes on pins 5 and 4. Ignition on, cruise on. Push and hold Resume button.
Should see 12V when Resume pushed, 0 when released. (Tests resume button)
Probes on 3 and 9. Ignition on, cruise on. Should see 12V. Push Brake pedal. Should drop to Release, returns to 12V. (Tests pedal) Push Clutch pedal. Should drop to 0. Release, returns to 12V. Switches)
Probes on 7 and 4. Raise one front wheel and turn slowly. Voltage switches between low (0-4V) and high (7-12V) skip this one. Tests wheel speed sensors and if you speedo works. Then this'll work too.
Here's the fun one. Out of the same type of solid wire, I made three little jumpers.
Jumper pins 9 and 11, 1 and 4, and 2 and 4 (do 2 and 4 last so you can pull it off and put back on easily) all at the same time. Ignition on, cruise on, vacuum pump will run, and should push gas pedal to floor. You'll notice vacuum pump is *loud*. Cruise off, gas pedal returns slowly. Cruise on, pump on, and gas goes back down. Press brake pedal. Gas will return slowly. Release, it'll go back down. Press clutch pedal. Gas will return slowly. Release, it'll go back down.
While it's all still running, pull the 2-4 jumper. Vacuum pump will stop. Gas pedal should remain on the floor. Wait. Gas pedal should stay pressed to floor. This indicates no
Vacuum leaks. Any of the above steps (cruise off, brake/clutch will relieve the vacuum, and replacing 2-4 jumper will fire up pump again) “

2. If the Bentley tests passes then it is supposed to be a problem with the module. Next pull the modules out of the car and look for bad solders (or any another issue that could causes these boards to crap).

3. With a multimeter measure the following on the board itself:
Pins – ohms (should be within about 10-15%)
2-4 - 1207
2-5 - 2030
2-8 - 2030
3-9 - 2200
4-5 - 825
4-8 - 825
5-8 – 1640

When I measured the 2 modules I have they where pretty darn close to those numbers.

4. next was the relay. remove the relay from the board carefully (you will need a soldering iron to do this).

This is the board when it is pulled out of the module. That thing in the circle is the relay.

The 5 solder joints that need to be removed (with a soldering iron)

What the relay looks like removed.

Once the old relay is removed, Drill about a hole 1/2” in the metal casing and thread 5 pieces of wire that is 10” long through the hole.

Next strip about 2-4mm off the wire ends and insert them the board where the old relay come off.

Now carefully solder the wires into place from the bottom side of the board.

VERY IMPORTANT!!! Label the wires like such (this will avoid confusion later on so you can hook up the new relay much easier)

Secure the wires with electrical tape (this also provides protection for them when they are run through the metal hole in the cruise control case). Personally I used a rubber grommet on the hole.

CAREFULLY feed the wires through the hole and push the board into the case (be careful not to allow the wires to wrap around components inside the case).

The new 5-pin relay ( I used a 12v 20/30amp ).
Wire # Relay terminal #
1 87a
2 30
3 87
4 86
5 85

1 is the one that is the closest to the middle of the board (near the pins), 2 is right beside #1.
3 is in the row of 3 on the edge of the board (the middle one is #3), 4 is the one closest to the "pin" side of the board and 5 in the only one left.

..................... 4 3 5
-- (pins)........... 2

personally I used a harness, but you can use shielded connectors, or tape the ends when finished (leave the wires labeled)

notice the wires labeled in case the relay needs to be disconnected, or replaced. Re-install the terminal door on the module and bend the tabs down to secure the cover.

I installed the module in the same location as the old one, and simply secured the relay with a zip tie in the same general area.
I took the car for a test drive and every time the cruise engaged and stayed engaged. The brake and clutch pedal switches work as well as the resume feature. I drove the heck out of the car and turned on and off the cruise (setting the first time and staying set every time).
All of the above information was found on the internet. I am not taking credit for it … BUT IT WORKS!

I have a 1994 Volkswagen Jetta. It has the same cruise module in it. My cruise was intermittently faulty too, would only work sometimes, usually only when its hot out, almost never when its cold, and random at best, 70-80% of the time it would not work. I did this exact repair (removed the old relay and installed a new one as described). The cruise works great, works 100% of the time I use it – IT WORKS PERFECTLY. As soon as the car gets to above 40 KM/H turn it on and BANG – it works 100% of the time every time if speed drops under 40 KM/H it turns off, apply brake it turns off, clutch it turns off, all switch controls seem to work (as far as I can tell all the safety stuff works exactly as it should).

I hope this posting can help other like me. This repair took me a total of about 90 minutes of my time (including about 30 minutes to do the “Bentley test”) I priced out a new module from a VW dealer here in Calgary, Canada - $748 + tax + 4 weeks to deliver it. This repair cost me under $10 CAD. The relay and harness cost me $5.99 at princess auto, and a few other dollars for solder, shrink tube, black tape, etc.

BEST OF luck friends… This works for sure 100%

Dar, from Calgary, Canada
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