First off, let me say I hope Rover Chris sticks around because his electrical advice is spot on i.e., his relay fix for non functioning tail and instrument panel lights.

Now I am having a problem of my own doing: my radiator fans comes on when I turn on the rear window switches in the center console (the windows now don't work). How did I do this? Well, I happen to have later model LR seats in my 96 Disco...these seats are electric, but they are not hooked-up because the SD orginally did not have power seats. To make the seats go forward and aft I tapped power from the center console switches namely the white and pink wire coming from the rear window switches and hooked that wire to a forward/reverse (reverse polarity switch). Something occurred in hooking this up (like a missplaced wire in the six terminal switch and I have lost the use of my rear windows. Also when I turn on the new seat switch, the seats don't move but the radiator fan comes on....if I turn on the window switch the same thing occurs. I have since disconnected the seat switch to the white and pink wire, but the power window seat switch only turns on the radiator fan.

Now I need to get my rear windows working again...note: I had already fixed my rear windows using the wire the well known fix using a relay bypass wire that I learned about in this forum.

Does anyone have an idea what I have done or how to proceed...I was working late a night and now I need some sleep.....


Thanks,

Mark

 

someone correct me if I am wrong, but doesn't the power for the rear windows come from a control module? The amp draw form the power seats may have damaged the window module. I guess I will go look at the wiring diagram and get back to you in a few.

Dodger

 

start checking fuses, then check for power going into the circuit. If you don't have a volt meter I would get a cheap one or even a cheap test light. this will tell you if power is going into the circuit thus telling you if the problem lies in your module or somewhere else.

if you did damage the module chances are you just burnt a trace on the circuit board, if this is the case and you know your way around a soldering iron, these burnt traces are usually visible and can often be soldered back together.

 

on a side note, I believe the radiator fan only turns on when one of two situations occur, either the engine overheats or the A/C is turned on, can't say for sure but maybe you are somehow triggering the A/C system. It may be worth throwing a meter on the compressor wire(?) or whatever part of the system turns on the fans to see if you are energizing it.

 

First of I just had a near completed version of this lost response based on a hyper sensitive touch pad on this borrowed laptop. Now I am smarter to write this in Word and paste it in.


Thanks guys for your tech tips.

I am determined to get this five thousand pound monster back on the road and out of my garage….so I will not give-up.

For my own review as well as for any suggestions from you guys here is where I am.

I had probably miss-wired a temporary reverse polarity switch (forward/back) to the consol switch for the rear windows and something went wrong and the rear windows don’t work, but the cooling fan comes on with each throw of the seat or the rear window switches….(I never checked if the fans turn forward or backwards switch-cause this is hopefully a temporary phenomenon!)
I had previously successfully completed the repair of the rear windows using the tech tip from Rover Parts.com That fix takes power from a white green wire at C2073 which also has a small blue/red wire that goes to the blower switch….and sure enough…when the blower switch is turned on….the cooling fan comes on but not the blower. So the white green wire connects to the K127 Ignition load relay….so I will investigate circuits associated with that relay. I will also open up and inspect all connectors associated and look for burn-outs…. I have never opened-up relays, and ECU’s looking for and resoldering burned out circuit boards…but I am handy with a soldering iron…

I will also look for a different power tap for the rear window lift white/pink wire which was cut and linked to the aforementioned white/green wire for the previous Roverparts repair. I am thinking of using a “extension cord” I made using a cigar lighter cord with a 10 amp inline fuse….hook the + to the white/pink wire and the – to a ground and test the function of the rear windows…sound ok?

My add-on seat forward and reverse switch will need a suitable power source….remember I have a SD model and the seats must be from a later model SE Disco so I don’t have the usual seat switch or wiring but this will need to wait until I get the cooling fan issure resolved.

Any thoughts will be appreciated….

Mark

 

Mark,

Since you asked I will express my thoughts on the subject. I have a 97SE that had intermittent rear window operation. I researched the subject long before finding this forum and found out that the Window ECU has a history of such failures due to fractured solder joints. Apparently the same joint fails in a high number of Discovery I's.

The Window ECU is located behind the glove box. I started my journey toward removing said ECU, only to find that it has one hidden mounting bolt at the top that makes it almost impossible to remove. I then found out that the circuit board could be extracted from the housing without having to unbolt the housing. Pull off the connector by squeezing the little tab on the side. Grab the edge of the circuit board with good needlenose pliers and gently pull straight back, it will unseat and come right out.

Do a good visual inspection of the board. On mine, it appeared to be good at first glance but pushing on a component lead, you could see that a small fracture existed that allowed the component to shift and the circuit went open. There were more than one marginal solder joints.

Using a cheap Weller soldering iron (pencil type), I carefully reflowed every solder joint from the pad to the component lead. Be sure to pre-tin the tip and keep it clean and don't overdo it with adding too much solder.

These boards were masss produced cheaply and just not a high quality like the military hardware that I spent several years working on. However, you can correct the problem quite easily.

Mine has worked fine ever since.

Let's review the "FIX" you did. I saw an ad for a bypass kit for something like twenty bucks that consisted of some splices, a little bit of wire and directions. Having been an Aviation Electrician in the Navy, a Manufacturing and Reliability Engineer in Aerospace and Defense Missiles, I was not about to pay twenty bucks for a few inches of wire, a couple of splices and somebody's jerry-rig bastardization of the electrical system. I merely dismissed the idea.

I was unaware of the details of the fix until I saaw your write-up. But you have confirmed my suspecions about such a fix. When you tapped into the blower circuit, you apparently implemented an undesired outcome with your "Engineering" Change. Most problems like this are caused by the previous type of modification, A quick easy one, but not well thought out and verified by testing.

We used to have a saying on the Cruise Missile Program that "Today's quick fix is tomorrow's next major problem."

My suggestion is to remove the modifications completely. Restore all original connections after fixing any insulation or conductor damage you may have inadvertently created.

Remove the window ECU circuit board and reflow all solder joints. Reinstall circuit board and test window operation. Reassemble everything.

As far as the power seats go, I would run a totally separate fused circuit of sufficient wire so as to not do any other incidental damage to something that may cost a lot to fix.

And if you think I was harsh or brash or whatevet, both my horse and I were High, as usual.

Anyway, hope you get it straigthened out and are able to enjoy your Discovery as much as I enjoy mine. Just be careful with jumping into modifications as you can really end up making some significant but totally unintended changes that you could quickly regret.

Thank you for allowing me to freely express my opinion.

 

Thanks Danny Lee, Your information is most helpfull. I will work on the window lift circuit board once I fix the blower/AC/cooling fan issue. My question is: What would I be looking for with a situation that the blower switch turns on the cooling fan and not the blower? Why wouldn't both the blower and the radiator turn on? I have been hesitant to turn on the AC switch, and the air recirculation switch, but my guess is they too will turn on the cooling fan and not the devices they are supposed to operate. Those switches are also deriving current from a white green wire that is at C2073 (the same wire that the rear window pink/white wire was spliced too...(but no longer).

Why would the cooling fans superscede the device that the switch is intended for? Also would it be best to track this from the cooling fan circuit starting at the fan themselves, or from the fuse that energizes the cooling fan.

Thanks for you help once again

 

I am a wee bit lost and slightly confused as to your current problem.

So you restored all the original connections, right?

And exactly what is going on now?

Way back when I first got my Discovery, I had purchased the RAVE from RN. I printed large sections and organized a few small to medium sized binders that I had on hand from old jobs to more or less catalogue all this info.

I printed the entire Electrical Troubleshooting manual and subdivided the schematics and such for ease of finding something specific later. I just recently took some time and started reading this stuff to resolve my new issues with the headlight switch and a couple of broken wires on my window switches which have been flopping loose without the center console in.

I do not like the way that LR completely fractured the overall schematic.
You really have to flip around from Power Dist to Fuse Info to Ground Dist to follow a simple circuit. And there is no overall schematic, so seeing the entire layout together is truly impossible unless you were to redraw it.

I am used to large aircraft and missile system drawings to T/S from, these fractured things are a royal pain to zip thru.

And the actual connectors in the vehicle are not labeled with the connector number, what a FUBAR.

I would totally review the AC blower and fan info. I know that when you turn on the A/C, both fans are supposed to come on. Also if the engine gets too hot, they come on at some preset point and stay on even with engine off until that overheat temperature switch deenergizes.

I have also seen other write-ups regarding the solder joints on the main ECU, but so far have avoided doing anything with that beast.

I am glad you found it helpful and did not take offense as some others have done with my blunt approach on various things. Happy to be a help to you. I am trying to be as graceful as a aging Redneck can be as he mellows out these days.

 

As a displaced hick myself, (parents from Kentucky and Tennessee) my hillybilly inclination was to simply tap the most convenient hot wire for the SE power seats in my SD was the rear window lift in the consule...turns out that wire also connects to the AC blower and cooling fan circuits as it energizes when the ignition comes on Thanks to the aforementioned splice recommended by rover parts.com . When I orginally tested the add-on forward and reverse switch hooked to the aforementioned window lift wire...the seats worked fine. When I returned a few days later to hook the seat switch again I think used the wrong wire of the six involved and that is when something must of shorted.....Then I hooked up the switch properly and that is when the seat switch started not to operate the seat, but it turned on the cooling fan at the radiator....the window lift did the same thing, and the blower switch too. So now the seat switch is disconnected, so is the window lift which is now disconnected from the Rover Parts.com tap. So now I find that the cooling fan comes on when the blower switch is turned on, but the blower does not come on...

so I am thinking of energizing the blower circuit separate from the cooling fan circuit....they share the same wire that energizes when the ignition comes on. this test should let me know that the blower circuit is intact.....that is: the blower fan comes on and the speed is controlled by the resistors as I turn up the fan speed.

I just don't know what to look for in a situation where a switch from a separate circuit turns on the wrong device. i.e., the blower switch turns on the cooling fans, but not the blower.

I am thinking damaged relay,,,,diode,,,,resistors in the blower switch....fused wires?
Any thoughts?

 

OK I think I am finally starting to develop the picture here a little, so you turn on the A/C switch and you hear your E-fans kick on in front of the radiator, but your blower motor under the dash does not turn on and blow cold air at you. how about heat, does it blow hot air? the blower motor usually has 2 wires going to it that will show + and - 12 volts when on, if you turn on the blower and test for power on those wires AT THE MOTOR, this will tell you if the motor is the problem, if there is power there then the motor is bad, if no power then you should move up the chain to the next component. the next component would be the blower motor resistor, check power there and determine if its the culprit, if not continue up the chain.

I would love to explain the complete system but I don't know it, I would merely jump on the rave electrical section and track the system from the fuse to the switch in the dash that you flip for A/C to the blower motor, and every component in between test for power at each (I would start with the fuse) and when you find the break in the chain where the power stops that should show you where your problem is.

now why would I start with the fuses and how would I check them? well a fuse is placed in a circuit to protect the wiring not the components if you overloaded (and/or shorted) a circuit and tried to draw too much power through the wiring (as it sounds like you may have) the fuse will blow so the wire does not get too hot and start to burn/melt
so checking fuses is the place to start, now how to check a fuse most people will pop the cover off the fuse box, look at the diagram and check the fuse that they think best describes the circuit they are having a problem with. Well they would be doing it wrong. best practice is to check each and every fuse. why is this? because almost every circuit has 2 fuses on it, a main supply fuse under the hood and a circuit specific fuse under the dash, and then many components may have multiple power sources which require multiple fuses, well these trucks have 2 A/C systems which when both activated turn on a total of 4 electrical motors (2 blowers and 2 E-fans under hood) that should be 3 fuses right there, then maybe 2 for the control units? I am not sure but if I was working on the problem I would start by checking them all.