Hello, I happen to have a Pierburg 1B3 and it's a bit of a pain trying to sort out the wiring for the autochoke and intake manifold preheater - here is how my engine bay looks in terms of wiring: 

 

Auto choke goes to the coil. 

 

Intake manifold heater goes to a ignition 12v feed. 

 

Idle cut off valve goes to ignition 12v. 

 

No idea what the brown/black wire is for. 

 

 

I've got the inline thermoswitch holder to be fitted, but not sure which wires connect to it. I guess Live Feed to one Switch, otherside to autochoke - but not sure how to wire in the intake manifold preheater, it's wire doesn't seem to reach to where the thermoswitch housing sits! 

 

 

 

 

The thermoswitch housing I have and the wires it came with: 

 

One red is the autochoke - the other red bridges from the white terminal. 

 

The white terminal connects to a live feed and provides power to both switches. 

I 

The manifold preheater is likely to be powered via a relay rather than direct from thermoswitch,  as it's quite current-hungry.

 

 

Can I ask what vehicle you’ve got and year as the photos don’t look like my 1989 Polo with a 1B3, so it’s difficult to make a visual comparison.I believe the 1B3 was fitted on the Polo 1.0 HZ engined model from around 1985. My coil is mounted on the LH inner wing, plus my choke housing looks a bit different to the one in the photos.

 

As Pete1 says and due to the current it draws, the manifold preheater is run via a relay(number 24)which on my polo is above the fusebox. This is controlled by a thermoswitch in the thermostat housing.The heater is a PTC(positive Temperature Coefficient) type, so as it heats up the resistance increases and the current it draws reduces.

 

On my Polo the wire going to the choke housing is shared with the +12v switched feed that controls the idle speed cut off valve, it doesn’t go to the coil. Both the choke and idle speed cut off valve get their +12v feed from a fused supply(fuse 9). If a throttle body heater is fitted on the 1B3(mine has one)then that will also share the same feed.

 

The coil supply isn’t fused, so I would have thought that there shouldn’t be a feed to anything other that ignition related items on the coil + terminal.

 

The Manifold Heater relay coil uses the same switched supply fuse 9, however, the +12v fed  to the heater itself  is unfused.

Edited 27 May, 20224 yr by mk2tastic

5 hours ago, mk2tastic said:

Can I ask what vehicle you’ve got and year as the photos don’t look like my 1989 Polo with a 1B3, so it’s difficult to make a visual comparison.I believe the 1B3 was fitted on the Polo 1.0 HZ engined model from around 1985. My coil is mounted on the LH inner wing, plus my choke housing looks a bit different to the one in the photos.

 

As Pete1 says and due to the current it draws, the manifold preheater is run via a relay(number 24)which on my polo is above the fusebox. This is controlled by a thermoswitch in the thermostat housing.The heater is a PTC(positive Temperature Coefficient) type, so as it heats up the resistance increases and the current it draws reduces.

 

On my Polo the wire going to the choke housing is shared with the +12v switched feed that controls the idle speed cut off valve, it doesn’t go to the coil. Both the choke and idle speed cut off valve get their +12v feed from a fused supply(fuse 9). If a throttle body heater is fitted on the 1B3(mine has one)then that will also share the same feed.

 

The coil supply isn’t fused, so I would have thought that there shouldn’t be a feed to anything other that ignition related items on the coil + terminal.

 

The Manifold Heater relay coil uses the same switched supply fuse 9, however, the +12v fed  to the heater itself  is unfused.

 

 

Thanks for the info, that's super useful. 

 

You're right. It's not a polo. It's a MK1 Golf. I came here as all the Golf forums only know about Webber carbs and I needed help from some experts. Heard this carb was fitted to a lot of polos, so here I am!

 

So, I think that brown wire may go to s relay for my intake manifold preheater - I'll check my fuse box tomorrow morning!

That would certainly explain the differences. 
 

Going from my carb manual I believe the Golf had a a 1B3 fitted to the 1.5/1.6 engine from 1981 to 84, also some Audi/Seat/MB models had it fitted.

 

If it’s not an engine/carb replacement job and is running it’s original setup, then you are probably going to need a wiring diagram to work everything out, plus a meter that can help you continuity test wires to work out where they go.

 

I’d definitely be suspicious of that wire to the coil though.Good luck with working it out, I can’t imagine the wiring set up should be much different between models when using the same carb with the same electrical requirements, but then you never know!

 

 

Edited 28 May, 20224 yr by mk2tastic