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Spezial-Forum zur Unimog-Baureihe U 404 S.

Moderatoren: stephan, krahola

Hello Hello

I fix the truck...it was my foult. I didn't attached Verteiler correctly .

I play with a little and the best/stable idle is at 5 deg.

Interesting is the way Jetronic controls the idle ignition advance . Vacuum line to Verteiler is controlled by solenoid. On 0 throttle solenoid is on and block vacuum to Verteiler, when throttle is applied solenoid shut off and vacuum is applied to Verteiler and respectively advanced ignition.....cool retro solution.

In next MonoJetronic models (golf 3, astra etc)...ignition is fully controlled by ECU (there is no weights and vacuum actuator in Verteiler)....just for the record.

I need to address alternator. This morning I leave truck to idle for an hour and 2 thing happend:
- engine temp not surpass 65 deg
- battery is not charging properly
...after hour I shut down the engine - restarted again - then shut it down again and start to turn real slow. Check the voltage on battery 11.8V.

I look the possibility's ...smaller pulley to alternator...mmmm... current is 50mm, smaller then that is not good for the belt and power transfer. To relocate alternator further front and to drive him thru cooling fan belt as far as fan pully is bigger...to much wirk. Don't know really.

If there is still a DC Generator in the Mog, it needs more RPM to deliver electricity.
Bretter Change to an AC Typ. It will charge even at idle.
The temp may bie a prob of the thermostate. Does not close ore opens at too low temp.
Put it into water with a thermometer on a stove and see when it opens.
Should at 80° to 85°C.

Gut Mog!
Hello MagMog,

The truck is converted to 12V (starter and alternator.....and VAG Mono Einspritzung). The problem that ECU targets very low RPM as far as is for 4 Zylinder Engine instead of 6 and 'see's 1 impulse more per RPM, so probably idle RPM's are around 750. It's complicated to rise the idle RPM's with this very old systems, as far as they are based on TPS and RPM (Alpha N) and when you mechanically rising the idle, you should adjust the 0 point of TPS sensor too.....which I don't want to mess with...for now!

Options are:
- mechanically rise throttle and readjust TPS sensor
- make smaller alternator pulley
- relocate alternator further front in order to be driven from fan belt
- connect ECU to separate Hall sensor (different from those one in Verteiler) which reads 2 points/toots on crankshaft pulley

need some help. When I tried to 'optimize' electrical system, I disconnect a lot things ...fuse box. So now I need wiring diagram, but with colors marking of cables. For now I was able to restore blinker, Innerbeleuchtung, horn... I still need to do lights (low, high, Standlicht, Stop, rear light, Scheibenwischer...so weiter.

I made some upgrade too. I install combi schalter to the steering column (from 207, 308 etc vans from the 80-ties)
schalter.jpg (60.34 KiB) 543 mal betrachtet
Hello Andrey
Andrey Nikolov hat geschrieben: So now I need wiring diagram, but with colors marking of cables.
google helps
(1.67 MiB) 14-mal heruntergeladen

I plaid this evening with idle ignition advance....try to rise idle RPM.

Unfortunately when I rise advance to 15 deg, the RPM's goes up, but engine is little bit 'shaky'.

When I set advance at previous 5deg, engine idles so smooth, that you can put a coin on valve cover :D :D :D :D.

After I deal with lights...next mini project will be...maybe:
- power steering from 406, I have all components already
- relocate radiator expander tank
- re-rout cooling hoses and new thermostat body (in which can be put different elements...easy to find)
- new pulleys in order to rise rpm's at alternator
- maybe electrical cooling fan
Hallo Andrey,

Thers are two reasons, why the cable from brake switch goes to the main light switch.
1. The 404 was a military truck. Therefore it was necessary for some reason to switch the normal brake light completely off.
2. The 404 has normally a combined brake and turn light.
On your attached diagram the cable to the back is shown on right side "Steckdose 12 polig für Aufbau u. Schlußleuchten"
The brake / turn light right is contact "I" with green/red cable
The brake / turn light left is contact "B" with white/red cable

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