So I've finally got my 16V to the point where it runs. I've done a full engine rebuild so I'm hesitant to run it for more than a few seconds at a time until I'm confident that it has good oil pressure. So each time I started it up, I kept an eye on the flashing oil pressure light in the dash to make sure it went out when idling. However, it doesn't. As far as I can figure out, the flashing light with no buzzer is the low pressure light, which should simply stop flashing when the engine reaches the right pressure at idle. Mine just keeps flashing even after idling for 10 seconds. The first thing I did to troubleshoot was to fit an external oil pressure gauge in place of the sensor and check what the pressure was at manually. Did that, and it was around 4 bar at startup. Knowing that the oil pressure is actually fine means that I can leave it idling for longer while I try and troubleshoot the oil light. Assuming that it is an issue with the sensor itself, which is a brand new sensor, I fitted the old sensor instead, but still the same problem. Next I tried unplugging the sensor and earthing it to the block, as I believe this is basically how the sensor works. Still the same issue. So I'm at the point now where I'm pretty sure it's either an issue in the wiring going to the light, or an issue with the gauge cluster itself. Does anyone have any idea for anything else I can do to try and find the cause of the problem? Obviously I'll check the wiring going from the sensor to the gauge cluster and make sure there's no breaks in the wire. But if I find that the wiring is ok, then presumably something in the cluster is the problem? Would this be likely to be something that can be replaced inside the cluster or will it be a case of replacing the whole gauge cluster? Any help is much appreciated.
Following my rebuild I primed the oil pump by using the old timing belt directly on the intermediate shaft alone and turned it at low speed on a drill and it took a little while to see oil to start flowing out of the galleries in the head (this was prior to installing the camshaft of course). Then before first start isolated the fuel pump and turned it over with the starter with the plugs out until I had good oil pressure on an external gauge. Perhaps remove one of the temp senders on the head and double check the oil pressure up there too just to be safe. Sounds like it is a wiring fault or a problem internally with the clocks. I did have this once myself and changed the clocks which solved the problem. I’d definitely be worried if the buzzer was sounding with the light flashing as that would mean both sensors were picking up low pressure. Were the clocks ok prior to rebuild or are they an unknown set of clocks?
Low and high pressure switches work in opposite ways electrically, and need to have the appropriate wires connected to each. Various bits of info in this thread: KR - the correct oil pressure switch...? | Club GTI
Coming back to this after a while, still no progress on the issue. I am confident that the sensors themselves are not the issue, as they are brand new, but also because whether or not the low pressure switch, which is the relevant one to my problem, is plugged in or not, the light on the dash does the same thing. That is, the oil pressure light flashes whether the low pressure sensor is plugged in, or unplugged. As far as I'm aware, the other switch would only activate the oil light if the engine is above 2000 revs or so. So at this point I'm assuming I either have a broken wire somewhere between the sensor and dash, or the instrument cluster itself is faulty. Does anyone know if the instrument clusters tend to give this kind of issue, and if so, is there a known fix? Of course, I'll test the wiring going to the cluster before I think about messing with the cluster itself.
If I were you, my next step would be to unplug the connector from the fuse box for the engine bay, identify the correct wire and do a continuity test between it and the plug on the sensor. If that test passes, I would reconnect plug to fusebox, and then test for continuity between instrument cluster plug and plug on sensor. If that test passes, I would reconnect the sensor, verify there is no continuity between the correct pin in the instrument cluster plug and the chassis. Start the engine, and then verify there is continuity. This will verify the wire is good, and that the sensor is good. And then if that test passes you can start looking at the cluster itself.
the light should only flash on ignition if the low pressure switch wire is earthed, which is the blue/black one. if the light still comes on with the blue/black wire disconnected then somewhere along the way its shorted to ground, your cluster wiring is bad or the cluster itself is faulty. first check is if the cluster has a good earth, on the CE1 fusebox it goes to a male spade near the fusebox then a female spade plugs into that and goes off in engine harness to earth on the side of the head. easy missed when things have been in bits
Right, finally got round to working on this issue again. It does not seem to be good news for my wallet. To recap, I have replaced both oil pressure sensors on my 16V with new, correct sensors. However, at idle the oil light in the dash flashes (no buzzer) I have verified that I do in fact have good oil pressure with two different external oil pressure testers, so that rules out the most obvious option. Next I checked the wiring to both of the sensors for continuity. I tested from the pin in the gauge cluster plug to the spade in the engine bay for both sensors, and both have continuity. So as far as I can tell, that rules out a wiring issue. So currently, I'm assuming that it must simply be a fault in the gauge cluster itself. Does anyone know if there are any common faults that could cause this? And is it likely to be something that could be repaired? I'd like to avoid replacing the whole cluster as that will get quite expensive. As a last resort I'll probably fit another new sensor just in case the first new one is faulty, but other than that I don't know what to do next.
next check, disconnect both oil switch wires. the light should stay off with ignition and when idling, then you should get the light+buzzer when revved over 2k rpm. if you then earth the blue/black wire, the oil light should be on with ignition, and when idling. disconnect the blue/black again then earth the yellow wire, now the light should be off ignition on & idling, and buzzer+light should stay off when the engine is reved over 2k. If all that checks out, the wiring and cluster is all ok, double check your oil switches are correct. the blue/black should go to a blue or brown 0.25 or 0.3bar switch, yellow to white 1.8bar switch. to test the low oil switch with engine off the spade terminal on the top should have continuity to the main switch body, then with engine running (over 0.25/0.3bar oil pressure) you'll loose electrical contact. the high switch works the opposite way round, so pressure under 1.8bar it will be open circuit, and over 1.8bar closed circuit
Coming back to this again, still with no solution. Since the last post more troubleshooting has taken place: Checked actual oil pressure (again) with an external gauge fitted to where the sensors go, all good there, healthy oil pressure at idle. Next I bought another two brand new sensors (0.3 bar and 1.8 bar) just in case either of the original new ones were faulty, but no change to the oil light. With the engine running I unplugged the sensors, but no difference to the light. Swapped the plugs (0.3 plug on 1.8 and vice versa), but no difference to the light. Assuming at this point that it is definitely an issue with the cluster, I started investigating it. Traced the circuits on the blue foil, to see where the 0.3 sensor input wire goes, found the end point of that circuit and checked continuity from the sensor spade to the end point of that circuit on the cluster, continuity all good. Checked the earth wire into the cluster for continuity with the engine block, and all good. Found the two pins that go into the oil light bulb itself, traced the circuit backwards from that point, checking continuity along the circuit to make sure there weren't any breaks in the foil. Found no breaks in the circuit. What I did find is that working backwards from the oil light LED pins, the circuit splits in multiple places, going to a pin which plugs into the rev counter, two pins into the speedo, and one pin into the main circuit board. I don't know enough about electronics to test the circuit board/rev counter/speedo, but all my other lights on the dash work, rev counter works and I think the speedo works (haven't driven the car yet). I'm kind of at the end of my knowledge by now, I've checked absolutely everything I can think of, and that I know how to check. There are no wiring problems outside of the cluster, as there is continuity between the sensors and cluster, and a good earth between the block and the cluster. The sensors themselves are not the issue, as two sets of brand new sensors has made no difference, and neither has simply unplugging them. The blue circuit foil does not have any breaks in it, and I cannot see any visible damage on any of the components that the oil light circuit goes to. The LED itself shouldn't be the issue as I've replaced it. I don't believe the main circuit board inside the cluster is the issue as I've replaced it with another one (although it was Motometer and the rest of my cluster is VDO). My only thoughts now are whether I'm either missing something stupid, or do I just need to replace the cluster? Replacing the cluster seems to be my only option unless someone knows someone who can inspect and repair them? The only other thing I'm unsure of is on the circuit foil. When tracing the oil light circuit from the plug, it simply ends at a bare copper circle on the foil. How does this work, and should it have something soldered to it? Any ideas appreciated.
I'm in Banbury, but thank you for the offer. I'm assuming for that to work the spare clocks would have to be from the same model as my car? I.e. CE1 16V clocks in MPH with the MFA screen.
Ah, mine are CE2, I missed that. I think they would just need to be CE1. I don’t think they would need to be MFA specifically.
sounds like the oil warning board has failed, it does happen. its shared with a fw other models but which one you need depends on the age of the cluster. as mentioned any ce1 mk2 petrol cluster will work regardless of if its mfa. it doesnt even need to have a rev counter most the non-rev counter clusters still have the light+buzzer warning system at revs, except for really early poverty spec dont but those are pretty rare
That's sort of a relief to hear, sounds like I don't have to replace the entire thing then? This oil warning board, is it just a separate circuit board or is it part of the main board inside the cluster?
yeah with the CE1 cluster its just clipped inside the speedometer so can be replaced separately let me know the age of the car, or I guess better yet any part numbers you can find on the foil as who knows if its original. could take the old board out to see whats on it, then reassemble into the car temporarily the cluster will still work just obv no oil warning
Ah perfect so I could probably just buy a Speedo from any petrol CE1 car and take the board out of it? It's a 1987 16V. Not sure about part numbers but I'm pretty confident the cluster is all original, and all VDO parts.
yep, from late 84 on its 321919064M, also found on post 84 cab and scirocco so its not toooooo hard to find
just unplugs, undo all 8/10 of the main screws then you kinda flip the back off, or you can click the 2 bottom plugs off the main cluster housing and it separates off completely which can make it a little easier. then theres a multi plug on the blue foil on the back of the speedo which pulls out of the oil board (carefully) then you unclip and remove the board from the side of the speedo harder to write it all out an explain than it is to do
I've had the whole cluster apart a couple of times looking for the problem so sounds like it should be no trouble. So does the part need to be from a CE1 car, I assume it does?
