- Oct 24, 2023
- 7
- 9
- Funster No
- 99,487
- MH
- Carado i338
- Exp
- Caravan since 2014, Motorhome 2025
hi all
I recently bought a 2020 Carado i338, hardly used, dealer said previous owners didn't take to motorhoming. Its my first MH, but 10 years experience caravanning , and I consider myself a "serious" DIYer (e.g. installed my own ASHP). Been learning a lot from this forum from those with Hymer built vehicles and things on mine are mostly the same, but not all.
e.g the fridge low power control wasn't permanently on: it was on the same feed as one of the lighting circuits, so when you hit the "everything off" master on the main panel... it turned the fridge off. So I've redone that line. Also the fridge 12v high power line is not via the Electroblok (EBL 31) - the often discussed EBL block for the fridge has nothing connected to its pins. Instead, its wired directly back to the leisure battery terminals (with a 20amp fuse at the battery end). The fridge relay on the EBL is unused - instead there is an automotive DIN72552 relay next to the EBL, which switches a permanent live (30) through towards the fridge's D+ line (87), when a feed from the engine D+ (86) goes high. proven this by putting a manual switch in parallel between 30 and 87, and as a side effect, I will have a way to run fridge from leisure when parked (yes I know 12v load will be high, but thats not the issue).
There are 3 other automotive relays next to the EBL under the passenger : one of them sends power to the side marker lights, one I haven't figured yet, and the other sends D+ to the Schaudt WA121545 B2B to activate it - except it doesn't, which is the subject of this post.
I swapped the existing old AGM lead acid leisure for a KSI120ah lithium which I had from my caravan. Checking everything over, went to check the B2B function... doesn't work. B2B never comes on. Multimeter out, checking everything, extreme puzzlement: All the large power circuits are fine, the issue is that the D+ input of the B2B is never being activated. and so I find that the automotive relay to activate the B2B is wired as follows:
30: from D+ of engine
87: to B2B D+ input
85: permanent 12v (not traced where from yet but definitely permanent)
86: vehicle end was loose (spade terminal loose from a large block, not obvious which one). Its possible I pushed it loose when tracing the fridge relay previously... no proof either way.
So I know why its not working, my puzzlement is why would it have been done this way in the first place?
obviously the loose one needs sorted, but the whole setup is very odd to me:
If 86 should be GND, then coil will always be active, 30 always connected to 87: having the relay is pointless???
If 86 should be a switched GND then it would presumably switch at the same time as D+ going high . And I've no idea if there is a switched GND to be had!
Either way doesn't isolate vehicle D+ from b2b's D+ input... so why is there a relay?
to me it would make a whole lot more sense and be a lot more "conventional" if it was wired:
30: perm 12v
87: to b2b D+ input
86: from D+ of engine
85: GND
which is exactly how the fridge one is wired (except 87 goes to the fridge obviously)
thoughts please?
I recently bought a 2020 Carado i338, hardly used, dealer said previous owners didn't take to motorhoming. Its my first MH, but 10 years experience caravanning , and I consider myself a "serious" DIYer (e.g. installed my own ASHP). Been learning a lot from this forum from those with Hymer built vehicles and things on mine are mostly the same, but not all.
e.g the fridge low power control wasn't permanently on: it was on the same feed as one of the lighting circuits, so when you hit the "everything off" master on the main panel... it turned the fridge off. So I've redone that line. Also the fridge 12v high power line is not via the Electroblok (EBL 31) - the often discussed EBL block for the fridge has nothing connected to its pins. Instead, its wired directly back to the leisure battery terminals (with a 20amp fuse at the battery end). The fridge relay on the EBL is unused - instead there is an automotive DIN72552 relay next to the EBL, which switches a permanent live (30) through towards the fridge's D+ line (87), when a feed from the engine D+ (86) goes high. proven this by putting a manual switch in parallel between 30 and 87, and as a side effect, I will have a way to run fridge from leisure when parked (yes I know 12v load will be high, but thats not the issue).
There are 3 other automotive relays next to the EBL under the passenger : one of them sends power to the side marker lights, one I haven't figured yet, and the other sends D+ to the Schaudt WA121545 B2B to activate it - except it doesn't, which is the subject of this post.
I swapped the existing old AGM lead acid leisure for a KSI120ah lithium which I had from my caravan. Checking everything over, went to check the B2B function... doesn't work. B2B never comes on. Multimeter out, checking everything, extreme puzzlement: All the large power circuits are fine, the issue is that the D+ input of the B2B is never being activated. and so I find that the automotive relay to activate the B2B is wired as follows:
30: from D+ of engine
87: to B2B D+ input
85: permanent 12v (not traced where from yet but definitely permanent)
86: vehicle end was loose (spade terminal loose from a large block, not obvious which one). Its possible I pushed it loose when tracing the fridge relay previously... no proof either way.
So I know why its not working, my puzzlement is why would it have been done this way in the first place?
obviously the loose one needs sorted, but the whole setup is very odd to me:
If 86 should be GND, then coil will always be active, 30 always connected to 87: having the relay is pointless???
If 86 should be a switched GND then it would presumably switch at the same time as D+ going high . And I've no idea if there is a switched GND to be had!
Either way doesn't isolate vehicle D+ from b2b's D+ input... so why is there a relay?
to me it would make a whole lot more sense and be a lot more "conventional" if it was wired:
30: perm 12v
87: to b2b D+ input
86: from D+ of engine
85: GND
which is exactly how the fridge one is wired (except 87 goes to the fridge obviously)
thoughts please?