Help with back of fuse board layout required
Discussion
Hi,
I have a problem with the modwise 2 stage cooling kit. Once the fans come on they stay stuck on at half speed when the Lo and Hi thermostats are off!! The only way to turn the fans off is by disconnecting the battery.
I have talked to David at Mod-wise and reversed engineered his kit. It seems the problem is with my TVR fan relays. My TVR is a 1994 Chim and TVR did a mod to the original fan power supply to stop the fuses blowing. Remember that? They added a second relay and fuse in the loom, in the passenger footwell, and wired it into the back of the fuse board. I suspect that this second relay is energised when the first fan relay switches power to the fan1. The second relay then supplies power to fan2. The problem is that David's kit joins the two fan power supplies thereby making the second TVR relay latch on.
In order to fix this I was hoping to move the trigger for the second relay from the output of relay 1 to the otter switch, as per fan relay 1. This should stop it latching.
My problem is when I took a look at the back of the fuse board I couldn't figure out what was what and whether I need special tools to make connections there.
Has anyone got any experience of messing around at the back of the fuse board? Diagrams and how to make connections there would very much appreciated.
David suggested just removing the second, added by TVR, fan relay. This does fix the problem but the power supply for both fans is then just through the one cable (pink). I was worried this could overload it??? Also, it would be better to have power to the fans supplied via two cables (both pink) as in the original design. Am I fussing over nothing??
For those familiar with David's kit I do have the 'full' version with the extra power lead from the alternator. This enables the fans to run on for a short while after the ignition is turned off. It also supplies power to the fans when they are on full power. I have determined it is not part of my relay latching problem but if I were ever to remove it eg forgetting that power to both fans is via relay 1 only, then power for both fans will only be via the one pink TVR cable and fuse! This is when I see there could be a danger of TVR wire meltdown or fuses blowing. I'd like to make the setup future idiot proof if possible.
ps anyone tried with the mod-wise kit making the fans run on until the lo thermostat is off instead of the hi thermostat off as David has it now? If yes.. were ther any problems eg battery drain?
I have a problem with the modwise 2 stage cooling kit. Once the fans come on they stay stuck on at half speed when the Lo and Hi thermostats are off!! The only way to turn the fans off is by disconnecting the battery.
I have talked to David at Mod-wise and reversed engineered his kit. It seems the problem is with my TVR fan relays. My TVR is a 1994 Chim and TVR did a mod to the original fan power supply to stop the fuses blowing. Remember that? They added a second relay and fuse in the loom, in the passenger footwell, and wired it into the back of the fuse board. I suspect that this second relay is energised when the first fan relay switches power to the fan1. The second relay then supplies power to fan2. The problem is that David's kit joins the two fan power supplies thereby making the second TVR relay latch on.
In order to fix this I was hoping to move the trigger for the second relay from the output of relay 1 to the otter switch, as per fan relay 1. This should stop it latching.
My problem is when I took a look at the back of the fuse board I couldn't figure out what was what and whether I need special tools to make connections there.
Has anyone got any experience of messing around at the back of the fuse board? Diagrams and how to make connections there would very much appreciated.
David suggested just removing the second, added by TVR, fan relay. This does fix the problem but the power supply for both fans is then just through the one cable (pink). I was worried this could overload it??? Also, it would be better to have power to the fans supplied via two cables (both pink) as in the original design. Am I fussing over nothing??
For those familiar with David's kit I do have the 'full' version with the extra power lead from the alternator. This enables the fans to run on for a short while after the ignition is turned off. It also supplies power to the fans when they are on full power. I have determined it is not part of my relay latching problem but if I were ever to remove it eg forgetting that power to both fans is via relay 1 only, then power for both fans will only be via the one pink TVR cable and fuse! This is when I see there could be a danger of TVR wire meltdown or fuses blowing. I'd like to make the setup future idiot proof if possible.
ps anyone tried with the mod-wise kit making the fans run on until the lo thermostat is off instead of the hi thermostat off as David has it now? If yes.. were ther any problems eg battery drain?
Edited by m4rk on Wednesday 18th June 10:24
I found this for this and post it here for anyone else looking for fuse box, board information.
http://www.parkersteve.dsl.pipex.com/fusebox.html
ps its very useful when dealing with the electrics. I'd recomend you print off a copy just in case you, or a sparky, need it in the future.
http://www.parkersteve.dsl.pipex.com/fusebox.html
ps its very useful when dealing with the electrics. I'd recomend you print off a copy just in case you, or a sparky, need it in the future.
Edited by m4rk on Wednesday 18th June 20:26
Why not just take out the relay that is energised by the wire from the otter, identify the two pins that energise it.
Work out which one is from the otter(the other would be earth) and trace it out the back of the fusebox, solder a wire into it and use that as a live trip wire for the second relay.
It would also mean that if the "wrong" relay packs up it wouldn't stop the other one working as it must do now?
Any good?
Work out which one is from the otter(the other would be earth) and trace it out the back of the fusebox, solder a wire into it and use that as a live trip wire for the second relay.
It would also mean that if the "wrong" relay packs up it wouldn't stop the other one working as it must do now?
Any good?
Hi Ribol,
It is a good idea because that is exactly what I am trying to do. Armed with the link I posted, Steve Heaths circuit diagram and my own TVR handbook I managed to trace all the wires to Block G on the fuse board.
The link I posted is extremly useful when trying figure out what connects to what. I'd made a hard copy of it for future use.. I suggest you do to. It shows what the pins in the blocks on the fuse board, fuses(upper and lower blade) and relays all connect to. The Bible shows which pin connects to what colour wire and where it finally ends up. The TVR handbook shows what the relays are supposed tbe for. All three pieces of info are required for a full picture of the TVR's wiring.
I located where the otter switch is on the the fuse board. It comes into Block G pin8 label 71 and then connects to the Fan1 relay 7 pin 35, which is the coil. This is then grounded when the otter switch closes thereby activating the original TVR fan1 relay.
Now I just have to figure out how to get a wire onto it and link this to the ground side of coil for Fan relay2. At the moment this I think is direct to earth and +12v side of the coil is hooked onto the 12v output to fan1 from relay1.
It gave me headache figuring out so I'm pleased you could follow it.
I think your only slightly wrong in that the wire to the otter is to earth, when the otter switch closes. The other side of relay1 coil is to +12v from the ignition feeds.
It is a good idea because that is exactly what I am trying to do. Armed with the link I posted, Steve Heaths circuit diagram and my own TVR handbook I managed to trace all the wires to Block G on the fuse board.
The link I posted is extremly useful when trying figure out what connects to what. I'd made a hard copy of it for future use.. I suggest you do to. It shows what the pins in the blocks on the fuse board, fuses(upper and lower blade) and relays all connect to. The Bible shows which pin connects to what colour wire and where it finally ends up. The TVR handbook shows what the relays are supposed tbe for. All three pieces of info are required for a full picture of the TVR's wiring.
I located where the otter switch is on the the fuse board. It comes into Block G pin8 label 71 and then connects to the Fan1 relay 7 pin 35, which is the coil. This is then grounded when the otter switch closes thereby activating the original TVR fan1 relay.
Now I just have to figure out how to get a wire onto it and link this to the ground side of coil for Fan relay2. At the moment this I think is direct to earth and +12v side of the coil is hooked onto the 12v output to fan1 from relay1.
It gave me headache figuring out so I'm pleased you could follow it.
I think your only slightly wrong in that the wire to the otter is to earth, when the otter switch closes. The other side of relay1 coil is to +12v from the ignition feeds.
Edited by m4rk on Wednesday 18th June 20:19
Ok, so you have switched earth from the otter. It sounds like a daft way to wire this up in the first place(not aimed at you), to be honest I would be tempted to remove the two relays and wire them externally properly using plugs rather than connectors and straighten out the mess once and for all.
Lets face it, a few more bits dangling in the battery area is hardly going to make it look untidy
Lets face it, a few more bits dangling in the battery area is hardly going to make it look untidy
I think they did it that way to stop both fans starting at the same time; presumably to reduce the current surge. It doesn't work really because I still get a brief dip in revs when the fans come on. TVR quirk!!
Also, I noticed that when the fans are swicthing off (before I had the mod-wise kit was fiited) fan2 carries on for good few seconds later.
I reckon there's a design fault in the setup. I suspect the back emf from the spinning down fan 1 is enough to energise the relay for fan2. So what you might think,,, but I think this could mean that when I am doing 70 and the wind is pushing the fans around, relay 2 will be energised by the back emf of fan1 and will therefore be powering fan2 even though the otter swicth is open!!!!!! Just a theory at the mo.
I wonder how may other cars of the 94 era had this after sale mod done by TVR or dealers. I guess you can tell by checking the passenger footwell for a relay tie wrapped into the wiring loom by the battery. Its a std yellow relay in my case with two pink wires, one red and one black. Pink is the switched power to fan2.
Also, I noticed that when the fans are swicthing off (before I had the mod-wise kit was fiited) fan2 carries on for good few seconds later.
I reckon there's a design fault in the setup. I suspect the back emf from the spinning down fan 1 is enough to energise the relay for fan2. So what you might think,,, but I think this could mean that when I am doing 70 and the wind is pushing the fans around, relay 2 will be energised by the back emf of fan1 and will therefore be powering fan2 even though the otter swicth is open!!!!!! Just a theory at the mo.
I wonder how may other cars of the 94 era had this after sale mod done by TVR or dealers. I guess you can tell by checking the passenger footwell for a relay tie wrapped into the wiring loom by the battery. Its a std yellow relay in my case with two pink wires, one red and one black. Pink is the switched power to fan2.
Edited by m4rk on Wednesday 18th June 19:53
Edited by m4rk on Wednesday 18th June 19:55
Ribol said:
m4rk said:
Hey Ribol,, what happened to your wise crack about Austrian softies!!
I thought it might have offended you, not my intention
In fact I thought it more of a compliment actually... not many bother to poke fun at me usually.ps I am English,,, maybe thats why I took it in a positive way.
Phew, that was close, well in that case get on with it you English softy
Seriously though, sometimes trying to put right something which has been done badly takes just as long as starting again and doing it properly. BTW the later cars have one relay per fan, that is how it should be.
Seriously though, sometimes trying to put right something which has been done badly takes just as long as starting again and doing it properly. BTW the later cars have one relay per fan, that is how it should be.
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