Throttle valve switch: interchangable?

SureFit Travis · Post by **SureFit Travis** » Sat Aug 19, 2006 7:44 pm

Okay, so I finally got into tearing down the 412.....and just in time. I was poking around the engine bay (engine running) and spotted a stream of fuel coming from the pressure regulator. Man, are those original hoses crispy. So $174 later, I have enough hoses to replace all vacuum and fuel lines, including a nice F.I. fuel pressure gauge.

I removed the intake runners to change the intake gaskets & injector seals, and decided to take off the intake plenum to check the throttle valve switch. Upon checking for resistance values across #9 & #20, I had nothing. Part failure. I cracked open the cover, and tried to clean up contacts, but the tiny pad just isn't bridging the gaps anymore.

The part number for my '73 EB engine is Bosch 0 280 120 021, or VW 022 906 111 B.

Where can I find a replacement?
Are these interchagable with other units?
Will one from a late-Bay bus work?
Will one from a Vanagon work?

Help!

Travis

raygreenwood · Post by **raygreenwood** » Mon Aug 21, 2006 9:29 am

I have a whole box of them at home. There are several that work fine and are only slightly different. The last three digits tell the tale. I beleive you can use the 021, 019 and possibly the 018. Iwill drop a post tommorrow after I consult my nores. Ray

SureFit Travis · Post by **SureFit Travis** » Mon Aug 21, 2006 6:21 pm

Hey, thanks Ray. I now realize that my late Bus/Vanagon idea won't work, as they'd be L-Jet, and totally diffferent.

I did, however, scrounge around my type-3 parts cars, and located one unit with the 5-pin plug. It's in really poor condition, and I only get continuity when rotating the arm over certain areas of the 'zig-zag' strip.

I've managed to find a source for a new one (they only have two left in stock, and are NOS Bosch parts), and don't know if this is the only/last place I can find them from.

I'm sort of uncertain whether I should just put another used one on, due to the uncertainty of how long it will perform for, or if I should splurge and pick up the new one.

Oh, and yeah, it ends in 021. The part numbers are in the first posting of this thread.

I'll check tomorrow for your posting.

Thanks,

Travis

SureFit Travis · Post by **SureFit Travis** » Thu Aug 24, 2006 7:49 am

Hmmm........well I guess I'm ordering the new one then........

raygreenwood · Post by **raygreenwood** » Thu Aug 24, 2006 8:15 am

Sorry...its been ugly busy at work. The 019,018,021 and 024 should all fit. There are slight differences to beware of though.

Some of the differences are noticable some not. I have not had time to lay all of them out and will not until tommorrow night....but I can tell you what to look for when cross matching.

On the 021...which I beleive is one of the better ones....the little tick marks that the wiper arm goes are...are wider by a few thousandths. This makes it much more probabale that teh speed of opening of the throttle does not causes skipping.

Other differences are that some are four pin plug and some are five. If yours is a four pin...you can use the five pin switch generally....but you must have the five pin plug housing so you can put your wires where they need to be. Also if yours is a five pin harness and you have a four pin switch.......you can also use it by removing the wire....#17 I beleive...which is deceleration fuel cut off.....but again you will need the four pin plug housing so you can sort the wires.
I remove # 17 anyway because that cut-off is a large part of teh "bucking syndrome" at part throttle settings.

Lastly.....the adjustment will be slightly different on some of these. The differences between switches are generally where teh wiper lands or parks itself when teh switch or throttle is fully closed. On acouple of models...you may actually need to widen teh slotted hole on the switch where the hold down screws go...but never more than a single graduation mark. This is because the actual half moon segment of the throttleshaft bushing on different models is in a slightly different spot by acouple degrees on different switches.
Friday night I will sit down with my box of switch variants...and do a list of teh four or five that can be readily used with only slight adjusatments and plug mods. Ray

SureFit Travis · Post by **SureFit Travis** » Sat Aug 26, 2006 11:41 pm

Would a type-3 unit work?

VW 311 906 111 D........Bosch #280 120 019 ?

Travis

raygreenwood · Post by **raygreenwood** » Mon Aug 28, 2006 9:09 am

Yes. That is the 019. It is the same unit.

By tehway..sometimes you find 019 or 021 or 024 units that have the 311 prefix...and others that have a 022 prefix. The difference between those two may genrally be a 4 pin plug vs a 5 pin plug for teh same part.

You can make....a 4 pin unit into a five pin unit....bu grasping the plug portion...tightly....and twisting it out of the metal baseplate clasp. It then pops into another TPS. The plugs units can be interchanged. Ray

SureFit Travis · Post by **SureFit Travis** » Mon Aug 28, 2006 6:11 pm

Thanks, Ray, I appreciate your info. I think I've located an NOS type 3 unit that will work then (the forementioned part number). The only difference visually is the angle of the plug (although both 5-pin).....but since you tell me it can be swapped.....I'm willing to give it a try.

Thanks again.

Travis

raygreenwood · Post by **raygreenwood** » Tue Aug 29, 2006 3:01 pm

Ah! yes...thanks for the reminder. The type 3 plug had teh up angle. This makes it hard but not impossible to plug in teh type 4 harness when the TB is installed.

But...you can "snap" that five pin straight plug off of your type 4 TPS. It comes off with a bit of effort. The metal fingers that make contact onto the ciruit board come with it. There are two "prongs" at the sides that hold this part onto the TPS. I reccomend getting a good grip on teh plug and twisting it. You can put the straight plug onto the the new TPS with just a little work. Ray