Rear Glass (engine lid) indicator light fault

[03 raw nsx]

Hi All,

The indicator light in the instrument panel will not go off when the rear glass hatch is closed.

I've checked the switch, it check fine. Shaken the harness, at least as much as I can access.
Shorted the plug to the switch and grounded both wires to ground. No help.

On page 23-150 of the service manual, it shows the circuit. Black wire to ground, blue wire to instrument gauge assembly.
I haven't check the continuity to ground in the plug (harness side). Thought about that while writing this
And my next step would be to check the wire on the other side of the firewall (behind the driver seat).

Has anyone else had this issue? Or is thinking of a better path to troubleshooting?

TIA
Rich Wong

 

[The King]

What kind of shape is your battery in? I had this problem when I drove my car home after getting it from the previous owner. The hatch light was on all the time,whenever I drove it.The remotes wouldn't lock the doors as it thought the glass wasn't closed. Fiddled with the switch, adjusted the latch, and got a new battery for the remote. Couldn't get the light to go out. I knew the battery had seen better days, as the car had to be boosted when I picked it up. Once I had it for awhile it became apparent I needed a new battery, as it went dead every couple of days, if the car wasn't driven. When the new battery went in, the light went out. And the remotes worked too! This may fix your problem.

 

[Old Guy]

The contacts in the hatch switch should be closed when the hatch is open and open when the hatch is closed. As such, if you disconnect the 2 pin connector to the switch and just let it hang down, the safety indicator system should interpret this as the switch being open and the hatch being closed. If the indicator goes out, then the problem is with the switch or short piece of wire between the switch and the connector (or the connector itself). If the indicator light does not go out, with the connector disconnected, it means that there is a short to ground in the wiring harness that connects to the switch or a fault in the indicator module. The next step involves getting under the dash so best to absolutely confirm that the switch is not the problem.

 

[03 raw nsx]

Did a switch test.
Open when switch is up (hatch open)
Closed when switch is down (hatch closed)

Connector test
Black wire continuity to ground good
Blue wire open to ground

I think there is a open somewhere in the Blue wire from the connector in the back to the connector in the indicator module.
Is the blue wire a home run to the indicator module? And it seems to also tie in to the security module.

 

[Moses]

Does pressing down on the glass turn the light off?

 

[Old Guy]

I think there is a open somewhere in the Blue wire from the connector in the back to the connector in the indicator module.
Is the blue wire a home run to the indicator module? And it seems to also tie in to the security module.

The wiring diagram suggests that the blue wire from the switch goes directly to the safety indicator module via a termination on the bottom of the instrument cluster. If there was an open circuit in the blue wire, the indicator light would not light up. When the hatch switch closes it completes the circuit to ground which causes the light to light up. Next step is to pull the connector off of the bottom of the instrument cluster and test the wire (check the service manual to get the right plug). If the wire back to the hatch switch checks out OK, then I think you are pretty much into removing the instrument cluster to get at the safety indicator module - yuck!

The safety indicator module does tie back to the security system.

 

[The King]

So you haven't swapped batteries yet? I'm telling you it fixed mine. Our cars may have a few things in common as yours wasn't born too far down the line from mine.

 

[03 raw nsx]

So it looks like there is a possibly a short to ground somewhere in blue wire run or a problem with the safety indicator module!
Thanks Old Guy

So you haven't swapped batteries yet? I'm telling you it fixed mine. Our cars may have a few things in common as yours wasn't born too far down the line from mine.

No, my battery is in great shape 14v. But to test your theory I disconnected it, waited and reconnected.
It was dead due to the circuit for the glass being sensed as open.

 

[03 raw nsx]

Update...
Continuity for blue wire (from connector to behind driver seat) good.
I have access to plug that goes into instrument cluster.

 

[03 raw nsx]

OK....
Manual says:
Switch open (hatch open)= continuity to ground
Switch closed (hatch closed) = no continuity to ground

So I disconnected instrument panel plug, hatch switch plug & security system plug.
Then tested continuity to ground...still shorting to ground

inspect as much of harness as possible from fire wall forward to instrument console - all looked good.
reconnect - still not working

reinspect & shake wire harness...reconnect all... working!!! normally!!!

anyone want to guess where the gremlin went?

 

[Old Guy]

I would check the wiring for chaffing where the wiring loom passes through the firewall, anywhere where the loom takes a sharp bend or is retained by a clamp. However, given the age of your car, unless you have driven it a lot or tracked it, I would not expect chaffing to be an issue unless there was an assembly error on the wiring harness (protective grommet slipped out of place or something like that). My experience is that Honda wiring is pretty durable.

The blue wire from the hatch switch goes to two places, the safety indicator module in the dash and the security control unit. I don’t know where the split to the two locations takes place. To be absolutely certain that the fault to ground is in the wiring harness, you should pull the plug from the security control unit to isolate it from the harness. However, the fact that you were able to make the problem go away by tugging on the harness does suggest that the problem is probably in the harness.

What is interesting is that the security control unit should be interpreting the ground on the blue wire as an open engine hatch and preventing you from setting the alarm. You didn’t report that as a problem. The indicator light in the safety indicator module is a LED. The LED requires very little current to operate and a high resistance connection to ground on the blue wire will cause it to light up; but, may not be enough to cause a problem for the securitycontrol unit.

High resistance /intermittent faults are an absolute pain to trace out! You have my sympathies.

 

[03 raw nsx]

I did check the wiring for chaffing on both sides of the firewall. I removed the evap canister that is just above the area where the harness goes into the firewall (that was a PITA! 2 of the 10mm bolts you can barely see! Time to R&R was 1 hour). And I removed the trim panel just below the "B" pillar (behind the driver's door) to access the front side of the harness. No chaffing, all looks good.

Actually I've been there before, when I routed a wire into the harness for my rear camera (wanted a clean install)

You are correct and I didn't mention it. The fault was preventing my alarm from setting and it drained by battery to zip.
If it comes up again, I will inspect the door sill to instrument panel. That is the only part I didn't check. Last resort would be to replace the wire from instrument panel to switch...ARRRGGGG

 

[Old Guy]

So, in some kind of case of bad transference, this problem has passed on to me!

This problem of the hatch indicator light coming on first occurred for me last year when I took the car out of storage. The problem stuck around for a couple of days and then disappeared without me taking any action other than checking the hatch switch and the wiring in that area for problems. The wiring and switch were just fine. Yesterday I got around to taking the car out of storage which involves reconnecting the battery and …. the problem is back. Its not a case of a weak battery after being in storage because the engine cranked over quickly and fired right up. However, it is odd that in both cases the problem emerged after the car had be in storage for approximately 5 months with the battery disconnected.

Right now I am just going to give it a couple of days to see if I get a repeat miracle. I really don't want to go tearing panels off to check for wiring faults.

I will be replacing the capacitors in my CCU this year which should allow access to the SCU for testing after the center console is removed. However, I was planning on doing that later. If the problem does not resolve itself I may have to move this up because I am not happy about the inability to are the security system if the problem persists.
[MENTION=9191]03 raw nsx[/MENTION] , did you unplug the connections to both the SCU and the safety check indicator (dash cluster) at the same time when you verified that you had a short to ground on the blue wire to the hatch switch? That is what your post #10 implies. If there was still a connection to the dash cluster I am wondering whether a capacitor leakage problem could be causing a short to ground; however, the presence of isolating diodes in the safety indicator would suggest that this seems highly unlikely.

Waiting to see what happens!

 

[03 raw nsx]

The first occurrence of this problem was on Dec 2014. After chasing ghosts for a month, at one point, I was so tired and fed up, so I just put everything back.
AND, the problem went away in the same mysterious way it appeared...all by itself.

...fast forward to Aug 2019. Problem reappeared. But I was busy working on my Stance Air Cups, so I ignored it. I took my battery out to trickle charge it while I was working on the cup kit, and when I put in the fully charged battery...the problem was gone. Coincidence? Weak battery and phantom faults...how is your battery? And ground cable?

 

[Old Guy]

Weak battery and phantom faults...how is your battery? And ground cable?

I have not done a formal discharge test on the battery; but, based upon the way the starter motor spun the engine I 'think' the battery is in pretty good condition. About 8 years ago I replaced both the neg and pos battery post clamps with much heavier clamps; but perhaps the negative cable ground to the body has some issues. One of the reasons I resist the 'battery problem' explanation is why only the hatch switch? If you look at the schematic for the safety check indicator the monitoring circuit for the hatch switch is pretty much the same as the door switches and the trunk switch. Why aren't they causing problems - not that I am looking for more problems :smile:.

Since you, [MENTION=25016]The King[/MENTION] and now me all appeared to have suffered / be suffering from the same mysterious problem and both you and The King had the problem go away coincident with doing something with their battery, I will acquiesce to the Gods of Coincidence to see if poking around with the battery does something.

 

[Old Guy]

The Gods of Weirdness prevail!

Rolling with the consensus results to-date, I loosened and removed the battery clamps, wiped the posts, squirted them with some grease and remounted the clamps and tightened them. Went around and stuck the keys in the ignition and turned to run and …problem fixed. My electrical engineer brain said 'what the hell is this nonsense'. My lizard brain said 'success'. The indicator for the engine hatch no longer lights up and the security system now sets. However, my OEM keyless was not operating. I wiggled the keyless wiring harness and removed and reseated the plug in the keyless unit. Still no operation. I pulled the keyless unit down allowing me to access the isolation diodes and the 3 amp fuse in the harness. Everything checked out OK. I disconnected the keyless unit and checked the status of the door, trunk, hood and hatch switch inputs at the keyless unit plug. Everything checked out correctly so I reconnected everything and retried the keyless unit and now it works. Two for the lizard brain!

 

[The King]

That's great to hear Old Guy! Hopefully your issues will be gone for good.

 

[Old Guy]

A little follow up. Went out to start the car up today and 'click' then nothing. My battery went from hero on Saturday to zero today. I love the ample warning provided by maintenance free batteries. But, germane to the original topic, as per [MENTION=9191]03 raw nsx[/MENTION] and [MENTION=25016]The King[/MENTION], maybe the weirdness with my engine hatch light was a portent of a battery about to shuffle off this mortal coil.

Too weird!

 

[The King]

A little follow up. Went out to start the car up today and 'click' then nothing. My battery went from hero on Saturday to zero today. I love the ample warning provided by maintenance free batteries. But, germane to the original topic, as per @03 raw nsx and @The King, maybe the weirdness with my engine hatch light was a portent of a battery about to shuffle off this mortal coil.

Too weird!

Yeah, I thought it was pretty weird also.

 

[neuronbob]

THANK YOU for this thread.

I tried to start my NSX after three weeks parked, and nothing.

I jump started the NSX and upon startup, the indicator for the engine cover was on, even though the cover was securely latched. A quick Google search brought me to this post. After trouble shooting as recommended above, I connected the battery to a tender and let it charge up for a few hours. I also cleaned up the battery terminals (they were starting a bit of corrosion).

Problem solved (for now)!

This battery is 2 1/2 years old, so even its reading 15-16 volts, it’s probably time to consider a replacement given this event.

 

[Old Guy]

Interesting.

Four owners with an apparent link between a dodgy battery and an open rear hatch warning light indication. The false indication is a small problem. The fact that it blocks the arming of the security system is a bigger problem.

 

[docjohn]

I recommend a tender for sporadic car usage..

 

[neuronbob]

I recommend a tender for sporadic car usage..

I usually keep my NSX on a tender when not in use. I simply forgot to do it this time. Completely my fault…d’oh!

I put my other fun cars into rotation the last three weeks…

Four owners with an apparent link between a dodgy battery and an open rear hatch warning light indication. The false indication is a small problem. The fact that it blocks the arming of the security system is a bigger problem.

In newer Acuras of the last 15-20 years or so, one of the first signs that a battery is dying is starting up to a “Christmas tree” of error lights. This comes up fairly regularly in the Acura forums and FB groups I frequent. I’m a little surprised to see this in an old Hondacura product. However, I’m happy to find this is a simple problem.

I’ll be monitoring the battery and definitely doing a better job of maintaining clean terminals…folks in the Prime FB groups indicate getting over ten years out of their batteries.

 

[docjohn]

Old guy remembers the day when a weak battery just meant your lights were dimmer...:biggrin: