I did ferget to reply to this ere fred. Thought I had but it was by pm (private message) to someone a long time ago. So ere's an eggsplanation of the continued fault finding which took place and what happened next.
Over the last week I have read through this whole fred to see where I'd got to in reporting back. Took a long time to read and brought back some happy memories. Some of it I remember as if it were only yesterday. Also a lot of ole names on the fred we dun't see about any more. I have also just realised I'm not that far away from celebrating my 15th year of Freelandering.
A quick recap about the fault… it was on a Freelander 1 2001 v6. When slowing down from say 30mph, with or without yer foot ont foot brake, at around 8 to 5mph, when the auto gearbox changes down from 3rd to 2nd gear, there would be a slight bang and bump feeling. This was intermittent and only happened occasionally. I can only describe it as a pronounced gear change as opposed to the normal smooth gear change which normally occurred. There were no other problems and the auto gearbox did everything else ok.
Jump to the last three paragraph's if yer want a quick answer. Or keep reading if yer want the thrill of the chase to find the fault.
There was a lot done to try to solve this ere problem. The following is near enough the full story. Get yerself a cup of tea.
At first it scared me into thinking the auto gearbox was showing signs of needing another replacement. Fer thems who dun't know… I had already had an auto gearbox replaced some years prior to this bump fault, costing £2,200 by a main dealer because mine were leaking. I din't know it were leaking. All I knew at the time was the gear changes occurred with a violent bang and it felt like someone had driven into it at 2mph. To cut the story short… the dealer din't tell me it was leaking either. The auto fluid would fall onto the engine guard and jump oft at speed. So there was never an oil patch under him. I ended up running it low on auto gearbox fluid a second time and feking the torque converter. When yer do this it slams brutally during gear changes. Hence why the down change fault discussed on this fred were a concern of things which may get worse. I hoped to fix it before it got more eggspensive. The topic of what the main dealer din't tell me is still raw to this day.
Please note it is NOT the same fault which caused the auto gearbox to be changed. It was a later fault which started 22,500 miles after the replacement reconditioned auto gearbox was fitted.
I constantly monitored my hippo with me Hawkeye for fault codes. None were available. This was annoying but it's down to what the car can sense and what the manufacturer provides int form of data yer diagnostic tool can access. I also monitored the live data with said Hawkeye but couldn't see anything different to normal when the fault occurred. All other gear shifts were ok apart from the one described above.
Initially I did the usual resistance tests and some partial auto gearbox fluid changes in the hope it would magically solve the problem. At first I thought the fault had gone. Then I thought it had reduced the amount of bump or it wasn't happening as often as before. After some miles of driving I realised it din't really make much difference. The auto fluid in it weren’t that old as it was new when the recon auto gearbox was fitted. So I din't eggspect a problem with it. I had started to notice the fault was more likely to happen when the air conditioning was on. Further testing… found this to be the case.
If you have found this fred and looking to change yer own jatco auto gearbox fluid in your Freelander 1 then the instructions are in the link below. Yer must use the correct method to set the level and use the correct bolt anorl.
https://www.landyzone.co.uk/land-rover/jatco-automatic-gearbox.69336/page-3#post-1055940
I performed all the usual resistance checks (instruction video below) on the auto and also monitored the engine computer and abs computer for faults. They both work with the auto gearbox computer to collect and report the required info for the gearbox computer to function as needed, by request from the engine computer to change up/down gears as required. There were some minor fault codes but these were cleared and never returned. It's not unusual for that to happen. None of the codes were related to the bump fault. The only one found was P1475 for the VIS balance valve int engine computer. The v6 has two VIS variable intake system motors which control valves dependent on engine revs/load and the accelerator pedal request. The car always had this pop up from time to time, from when I first had it many years ago, without problems, so it was ignored. Both values were tested and they operated ok with my Hawkeye controlling them.
resistance video = Freelander 1 v6 Jatco Auto Gearbox - Measuring the Solenoid and Sensor Resistances
The bump fault continued. As time went on I came to the decision the fault was related to the gear change but not the fault of the auto gearbox itself. After all… the gearbox performed faultlessly for the majority of the time. It was only occasional the bump fault would happen. Something like 1 int 20 stops. More likely to happen when the air conditioning was switched on.
There's a lot of talk ont web about resetting the auto gearbox computer by disconnecting the power to it but this doesn't work. The auto gearbox computer is powered via fuse 4 and relay 4 int engine bay. Relay 4 switches oft when yer switch oft the ignition (or shortly after). Hence the auto gearbox computer powers down. There was also a suggestion my bump fault could be related to "adaptive" features of the auto gearbox computer. It can sense and adapt gear shift pattern to certain conditions like knowing if it's driving the FL1 downhill, uphill or towing etc but it doesn't have the more modern driver monitoring adaptation options like the later FL2 does. Although quite modern at the time it was developed... it dun't have the adaptive features of bigger LR's and other vehicles like merc's from the same era. It was also suggested it may have a firmware bug causing my bump fault but that would be very unlikely as at the time my car was the only one we knew of with said fault. If there was a firmware bug then you would eggspect it to effect loads of Freelanders with the same fault. It don't.
Still dismissing the auto gearbox as the cause of the fault I moved towards looking at the electrics. I was convinced I had an intermittent electrical fault. But finding it was going to be fun.
Relay 4 int engine bay fuse box powers lots of items/fuses. Via fuse 4 this includes the air con compressor clutch, computer fan, several engine sensors and auto gearbox computer including it's solenoids and sensors. So there's a long list there of items associated with the control/monitoring of the car when me bump fault occurs. Initially Relay 4 was replaced for another as this is the common point for all items to be powered but the same intermittent bump continued. I tried measuring the voltage out of fuse 4 as a reference point and a few other places while driving. The value moved around too much so the meter was changed for a more precise 4 wire sense version. This gave betterer results but din't pinpoint a blip int voltage at the time of the intermittent bump. Mainly because the meter int fast enough to respond. I was also conscious that tampering around int electrics could disturb the fault so we had to keep waiting fer it to appear again before moving the monitoring wire to measure a different part of the circuit.
We measured a volt drop across the fuse box which was higher than eggspected. Not surprising to have a bit of a drop in there due to all the relay and fuse connections. But the drop was a bit too much so this made me wonder what was in there that could cause this. With the fault being intermittent and more likely to happen when the air con was on, we were thinking the eggstra power demand of the air con was a factor or related to the cause of the problem. Hence the volt drop across the fuse box being of interest to us.
I took the engine bay fuse box out so we could take it apart. Theory being I may find something inside like a broken connection. Years ago peeps talked about engine bay fuse boxes suffering from rust. Never seen this before myself but it was the next logical step. In the end the fuse box looked ok. All the fuse and relay terminals inside were squeezed together to make them grip the fuses/relays betterer once refitted. Some info and pic's ont taking it apart int this fred:
https://www.landyzone.co.uk/land-rover/engine-bay-fuse-box.254159/
The fuse box was put back in the Freelander and everything connected up again. Relays and fuses put back in the same positions. We measured the volt drop across the fuse box again. This had now reduced to a lower value which we were happy to see. The intermittent bump problem continued. Not as much as before but still difficult to detect due to its intermittent nature. It was annoying to know running the air con made it more likely to happen. Switching oft the air con and running lots of other electrical items like the headlights and heated seats din't. This would question it being a loading issue. The alternative would be the air con pump slowing down the engine. Turning this by hand with the clutch engaged din't show any signs of a problem. It would need to be a significant problem to do this as well as quite magical to only cause a problem on one particular gear change.
Thinking back the work done to the engine bay fuse box did reduce the chance of the fault happening. By this point I was convinced there was an intermittent electrical problem but still couldn't trap it due to its intermittent nature. One of the biggest issues I had was getting the car to change down from 3rd to 2nd gear. Yer can't do this while stationary using manwell control of the auto gearbox via the auto gear box lever. You can select 2nd when stationary but not 3rd. The fault din't happen on any other gear change.
I took the wheels oft and sat ma hippo on ma HippoRamps (TM) so I could drive it when stationary. This allowed me to go up and down the gears with the engine driving the gearbox/ird etc as normal but the fault just wouldn't occur. It was a "try it and see" idea which I've done before to try to find ma hippo's transmission squeal. Looking back it seems mad to do this but the bump fault was bugging me and I weren’t going to be defeated. With no air flow it makes the engine get hot very quickly when yer do this. That’s something to be careful of if you don't have a large fan on it.
Earlier on in the fault finding I'd noticed the bump fault was more likely to happen with the air con running. By now I was 100% convinced this was the case. I could switch the air con on or oft myself, int order to choose when the fault would occur on the down change from 3rd to 2nd. There's several gear changes like this on the way to and from work so it had at this point become a daily ritual to choose when to make the fault happen or not by switching on/oft the air con, while driving too/from work each day.
I had already followed the wiring all over the engine bay to see if it were snagged on anything. I'd tried running it stationary ont tick over and wobbling all the wires. Be careful where yer put yer hands if yer try this yerself as the various moving parts like the auxiliary belt will pull you or your clothing in if you get caught in it. Unfortunately it din't trigger the fault or show any signs of a potential problem.
We also tried testing some of the local wiring harness wires with an earth bond tester to see if they were capable of supplying a reasonable load current of many amps. I have access to all sorts of toys like this at work so we had a go. It proved the wiring was good but din't show up any faults. One thing we did notice was the fault became more intermittent after this. So we must have disturbed it.
Historically ma hippo has had a replacement engine at a LR main dealer. They use the easy method of pulling the engine/auto/ird out as one lump and swopping the engine over, then putting it all back. The same process happened when the auto gearbox was changed. Perhaps more than once as they had problems and wouldn't give it back. With so much activity in the engine bay over the years I was still convinced I had an intermittent wiring problem and concerned about previous work being a possible cause.
The issue of the air con being involved in determining if the fault occurred was still playing on me mind. When it was on I din't really know if it was actually on and "running" the process of cooling the car. I knew when the air con fans were running and the dash vents supplied with cold air. Me Hawkeye reported back the correct status of the air con clutch request to switch on or oft the air con. But I was still a bit suspicious of the air con so wired a switch int series with the control wire which powers the air con compressor clutch magnet thing. I could then drive with the air con on but disable the clutch manually as I was braking. It din't prove anything one way or t'other so I then drove it with the windows open and the air con demand on full to make sure it would be running when braking. Again the Hawkeye never reported it switched oft so the process must have still been running. Sometimes I would only put the air con on just before braking. The cool air would still start to come through… which to me said the air con was running while braking and not switched oft due to braking.
Fer a while I put the problem to one side. I drove around as normal and switched oft the air con when braking. The bump fault never happened when I did this. If I chose to leave the air con on it did. So that to me was proof it were an electrical problem and related to supplying power, because we had ruled out every other possibility by process of elimination.
I then hard wired in some current measuring devices from work. These are precision cut mounted metal plates with a specific resistance. Can't remember the propper name of them but yer wire them int series with a load and measure the volt drop across the precision resistor. They measure something like 0.01ohms so a volt drop of 0.2volts across it means there's 20amps flowing through it. The resistance is low so as not to affect the circuit it's wired into. I have some that allow yer to measure several hundred amps like this so quite useful as a test tool.
Now yer probably thinking this is mad and over kill but it aint. We used a scope (oscilloscope = measures voltage against time and displays it as a graph) to monitor said precision series resistor in order to know the precise volt drop across it, and therefore the current through it. Add to this we already knew the volts flowing out of fuse 4 meant we could monitor demand via said fuse and relay 4. Din't take long to spot the volts dropping with current increasing while driving and different things happening to the car.
We then realised the volts out of fuse 4 had dropped again. Also when switching on the air con the volts would drop further as the current increased. There was also a blip of current and drop int volts at the same time the bump fault physically occurred. Messed about with this for a while whilst looking at the current drawn int general use. Got side tracked a bit ere as I have an general interest int auto's but the result was clear. We then monitored the voltage before fuse 4 and changed relay 4 for another. This had been done previously with the sunroof relay (wasn't used as fuse pulled out) but this time the relay fitted din't have much of a volt drop across it's contacts.
We then went back to measuring the output of fuse 4 and witnessed the same blips as before when the bump fault occurred during braking. But the volts out of fuse 4 dropped again. We then found there was a volt drop across fuse 4. Took said fuse out to check the connections were tight and they were. Put fuse 4 back in and the volt drop across fuse 4 disappeared… then it came back. Fuse 4 was then replaced. The volt drop across fuse 4 then almost disappeared as you would eggspect. We couldn't see anything wrong with fuse 4. He's a normal fast blow car type fuse. The resistance across him was near enough 0ohms as eggspected.
Suspecting the fuse box to be the problem we fitted and removed the new fuse several times but the volt drop across it din't return. The original fuse 4 was then put back in and the volt drop across him appeared again. Cutting the story short… if yer measure the resistance across fuse 4 with croc clips on the metal tags and leave him to relax on the table… he would measure somewhere around 4 to 6 ohms more than he should. He's 15amp rated so we tested him at 11amps briefly which he passed ok. Only briefly as we din't want to destroy him. The little bastid must have a poor connection which we assume is between the metal tags and the fuse wire. So he was permanently replaced. The resistance value measured ont table doesn't match his volt drop when int circuit but at this point it was too late to care.
Things had improved but we still wanted to find the blip which caused a pulse volt drop. We made a list of all the items/sensors etc powered by fuse 4 and started looking at them using the engine live data via me Hawkeye. Eggsample video's of this ont you tube. As if by magic the balance value operates at the same time as the 3rd to 2nd down change when slowing down, most of the time we watched it. Bastid.
We then used me Hawkeye to control both VIS values and they both gave a blip int current and caused a drop int voltage when ma hippo was stationary. Bit more than we thought they should. Both VIS were taken apart and the usual oil residue etc found. Cleaned up and put back and tested. Also all the other items we could get to with electrical contacts we could remove, clean and tighten up, had this done to them anorl. As ma hippo's been oft road quite a bit we also cleaned up the radiator fan and fan controller connections. While checking the volts and current again after doing each item yer could see a slow improvement. The relay/fuse volt drop was reduced compared to previous measurements and the volts out of fuse 4 din't drop as much as previous. Several road tests over the following weeks proved the bump fault had gone.
So to conclude… through process of elimination to find an intermittent fault which only occurred while braking… we found a number of concerns. Some of them caused by general wear and tear. Some cleaning required due to dust getting into connections and potentially causing trouble. The result of this cleared the bump problem int several stages.
Connections tightened up int engine bay fuse box. Relay 4 may have had early signs of contact wear but not much. Fuse 4 measured something like 4 to 6ohms causing another volt drop. Connections to the VIS motors, air con clutch and air con controller etc… and radiator fans all cleaned up and tightened... which further reduced the volt drop. VIS motors/switches cleaned up and oil deposits removed. Yer could still see a small blip of current when the VIS operated with or without the air con running. But after the clean up and tightening yer din't get the volt drop we had before. Bump fault solved.
Yer probably wondering if the problem ever came back. It din't. Ma hippo continued to perform as I would hope with smooth gear changes thereafter. The bump ont down change from 3rd to 2nd disappeared and everything was performing ok. This continued fer a while until he decided to start mixing his coolant with his engine oil. Only very very slightly but enough to p*ss yer oft. It weren’t head gasket failure. But that’s another painful story for another chapter in ma hippo's life.
