Map sensor

Stampey · Jul 13, 2018

Ok thought ide start a nes thread as old one was exhausted.
Trying to trace a fault on my fl2 td4
Fault being terrain response faulty followed by fuel gauge drop.
Normally happens after driving 4 to 10 miles on average.
Been checking alsorts on the car but if I unplug the MAP sensor and start up I get the same faults almost sraight away. Could it be it's faulty. Any ideas how to check if it's working. Thanks in advance

GrumpyGel · Jul 13, 2018

I know nothing about the F2's electronic "wizardry", but what lead to you to try unplugging the MAP sensor to diagnose this fault?

Nodge68 · Jul 13, 2018

Have you run a full diagnostic check on all systems? Not doing so will just wast your time and will exhaust multiple threads on here.

If your planning on keeping your FL2 for any length of time, then buy yourself a Gap Diagnostics IID BT diagnostic device. There're expensive but in valuable for all system diagnostics on the FL2 and when you sell the FL2, there's a good market for second hand IIDs, with them achieving 75%+ of there original purchase price.

Stampey · Jul 14, 2018

Read somewhere that a faulty MAP sensor can give a terrain fault.
Not got a scanner but have had codes read several times by a local indy.
On a budget so can't afford a scanner at this moment in time.
I know unplugging sensors is not the right way to diagnose but by unplugging the map it gave me the same symptoms that are putting the truck in limp mode.
However I also tried unplugging the MAF last night and got same results so maybe it's a bcm or instrument pack issue.
I might send the instrument pack for test and repair first?

GrumpyGel · Jul 14, 2018

Stampey said:
Read somewhere that a faulty MAP sensor can give a terrain fault.
Not got a scanner but have had codes read several times by a local indy.
On a budget so can't afford a scanner at this moment in time.
I know unplugging sensors is not the right way to diagnose but by unplugging the map it gave me the same symptoms that are putting the truck in limp mode.
However I also tried unplugging the MAF last night and got same results so maybe it's a bcm or instrument pack issue.
I might send the instrument pack for test and repair first?

I believe JLR have financed the building of their new massive factory in Eastern Europe by selling BCMs to fix faults in F2 that were actually caused by other bits on the car's many networks such as wiper switches or blown bulbs.

Nodge68 · Jul 14, 2018

Without a thorough diagnostic session with proper equipment, you'll be wasting your time. You can't simply unplug random sensors and expect it to solve the problem. All that will do is cloud a true fault with a host of non-faults from the unplugged sensors. The FL2 is a complex vehicle electronically, so correct electronic diagnosis is essential, if you want to get to the bottom of any issues. Unfortunately it's not the sort of vehicle that can be run or maintained on a shoestring, especially when electronic issues come up.

Stampey · Jul 14, 2018

Point taken
But I've already spent 1k on repairs by listening to experts....
Will be getting an auto electrician soon as a last ditch attempt to fix it......

Nodge68 · Jul 14, 2018

Stampey said:
But I've already spent 1k on repairs by listening to experts....

If you've spent £1K on repairs suggested by experts and it isn't fixed, then they're not experts IMHO. Unfortunately with the complex electonics in modern vehicles, more specialist equipment is needed to find faults.
Have you taken it to LR for their diagnosis?

Stampey · Jul 14, 2018

Nodge68 said:
If you've spent £1K on repairs suggested by experts and it isn't fixed, then they're not experts IMHO. Unfortunately with the complex electonics in modern vehicles, more specialist equipment is needed to find faults.
Have you taken it to LR for their diagnosis?

Yes main dealer said fuel sender B so I had both changed by an indyv as it was cheapee but fault still there

Stampey · Jul 14, 2018

There's one area I need to revisit. When inspecting the wiring harness in passenger footwell I unclipped the harness checking for exposed wires all seemed ok but when I started here up and moved the harness left to right the fault kicked in. I should look at that again as at the time I thought it was just a coinsedence.....I have checked all the splices about 4 from memory. They were all sound.

guineafowl21 · Jul 15, 2018

We were tracing a voltage drop in the throttle sensor line in the other thread - you’d nailed it down to the bcm. Any further progress on that? It could be as simple as a cracked/dry solder joint on the bcm pcb. Pics?

The lead-free solder they use now doesn’t hold up well under vibration or thermal cycling - ie the conditions inside a car.

Nodge68 · Jul 15, 2018

guineafowl21 said:
The lead-free solder they use now doesn’t hold up well under vibration or thermal cycling - ie the conditions inside a car.

Basically lead free solder is rubbish. I'll not use it on any of my project, as it's just too unreliable at making permanent joints.

The Mad Hat Man · Jul 15, 2018

Nodge68 said:
Basically lead free solder is rubbish. I'll not use it on any of my project, as it's just too unreliable at making permanent joints.

No, it’s not. It just needs a different soldering technique, but if you aren’t worried about your lungs or the environment, it does flow better.

guineafowl21 · Jul 15, 2018

I’ve fixed a good few circuit boards just by blindly reflowing all the joints. If it’s got RoHS on it, and you can’t find the fault, reflow it.

Ironically, the RoHS legislation has removed lead from solder but increased the amount of electronic waste, from premature failures that no-one can be bothered to troubleshoot.

Still, it’s made all that waste safer. No more lead can only be a good thing. Thank goodness it’s not used for roofing and water pipes...

guineafowl21 · Jul 15, 2018

The Mad Hat Man said:
No, it’s not. It just needs a different soldering technique, but if you aren’t worried about your lungs or the environment, it does flow better.

You can get used to using it, but the joints are not as long-lasting, especially under stress/vibration/thermal cycles.

If you solder a lot, you should have an extractor anyway. The flux fumes aren’t good for you.

The Mad Hat Man · Jul 15, 2018

guineafowl21 said:
You can get used to using it, but the joints are not as long-lasting, especially under stress/vibration/thermal cycles.

If you solder a lot, you should have an extractor anyway. The flux fumes aren’t good for you.

I know. It was my business for over 30 years

.

I think it says something that most military spec PCBs are exempt from RoHS compliance.

Nodge68 · Jul 15, 2018

The Mad Hat Man said:
No, it’s not. It just needs a different soldering technique, but if you aren’t worried about your lungs or the environment, it does flow better.

Fluxes used for lead free are more harmful and caustic than the simple Rosin flux used for 60/40 solder.

guineafowl21 said:
I’ve fixed a good few circuit boards just by blindly reflowing all the joints. If it’s got RoHS on it, and you can’t find the fault, reflow it.

Ironically, the RoHS legislation has removed lead from solder but increased the amount of electronic waste, from premature failures that no-one can be bothered to troubleshoot.

Agreed. Often one small change to a material used in manufacturing, causes a huge environmental problem somewhere else.

guineafowl21 said:
You can get used to using it, but the joints are not as long-lasting, especially under stress/vibration/thermal cycles.

Agreed. Lead free solder isn't as good as leaded, hence more scrap electronics going to land fill.
I only use leaded solder and have done for 40 years, I'll not be changing that any time soon.

The Mad Hat Man said:
I think it says something that most military spec PCBs are exempt from RoHS compliance

Contradicts your previous statement that MHM.

The military want components to work without long term reliability issues. I strongly suspect that all electronic components are soldered with traditional lead solder, hence no RoHS compliance can be applied.

The Mad Hat Man · Jul 15, 2018

Nothing contradictory.
Military PCBs are exempt from RoHS compliance as most of their boards are built using Leaded Solder due to the working environment. Most PCBs are not in that environment and can be built using lead free solder to reduce the harmful effects of lead in the environment. It can be more difficult to work with, but if using the correct equipment, those difficulties are minuscule.
For the home user, leaded is easier.

Stampey · Jul 15, 2018

See post has turned into a soldering debate lol!
Bcm looks good, although it's a two layer pcb component and you can't see everything.
Used a magnifying glass and covered what I could see.
I know I've probably shouldn't unplugged sensors as part of troubleshooting but I still don't understand why unplugging the Maf or Map shuts down terrain response and makes the fuel gauge drop...
I would have expected the engine to run a little rougher but that's all?
Re the acc pedal voltages are correct at 5v volts and 7 volts on the two circuits.
It's the way landrover designed it apparently.

td4van · Jul 15, 2018

Unplugging an engine management sensor will mean the car doesn’t know what is happening so it cannot run terrain response programmes correctly which is why it flags a fault.

Not sure why it drops the fuel gauge to zero though as that is an unlinked system hardware wise to the MAP sensor

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