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Help! '89 Vette Has No Underhood Lights or Cornering Lamps

DarkRed89Flyer

Active member
Joined
Mar 3, 2011
Messages
33
Location
Mesa, AZ
Corvette
1989 Dark Red Coupe
Hello All!

I just bought my dream car a few days ago! An '89 Dark Red Coupe w/ Black Leather Interior with just over 100K miles.

First, let me say that what I put in the subject line is true, although the headlights/parking lights/fog lights work perfectly. When I turn on the turn signals, left or right, neither cornering lamp comes on. Also, when the hood is raised, the underhood lamps don't illuminate. I thought these were supposed to come on as soon as the hood was opened, by way of a mercury switch, but I can't find it.

I already tried the most obvious by replacing the bulbs, but that didn't help. My next stop is the fuse block. If that isn't it, do any of you have any other ideas?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Thanks for your feedback everyone! I was able to discover that indeed the weatherpak connectors for the underhood lamps had been disconnected. Now the lights work, but I'm wondering were to get the gaskets to seal the lens against road grime from getting inside the housing. Both of the lenses were blackened by dirt and "gunk" from the engine bay & the road. I've searched the catalogs at Corvette Central and Mid America Motorworks and can't find a reference to them being available. I could make my own, but if they're readily available somewhere, I'd rather do that, at this point, than to invest the time in this, when it would be well-spent on re-upholstering the seats.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To my surprise, the cornering lamps do work! Nothing is mentioned in the Owner's Manual about them only working at night. I happened to be following a dark-colored Toyota truck the other night and was able to see the reflection of my 'Vette in the tailgate when I pulled up behind him. When I turned on the turn signal the cornering lamp came on. It was the first time I'd driven after dark.

Now, however, I have a different problem. I drove the car on a trip over the weekend. When I was getting ready to leave my home, I started the car right up, but it died almost immediately. After that, it wouldn't start. I tried 2 or 3 times and it wouldn't "catch." I finally did get it started after waiting about 10 minutes. On the way back home, yesterday, I stopped for a food/restroom break, and when I tried to leave, it wouldn't start. It would crank, but not fire off. In addition, the turn signal & high-beam indicators were on solid and the gauge cluster had no backlights. The headlights were not on. I'm thinking that my no-start issue is probably the need for a new fuel filter. It has 104K miles and I'm unsure when it was last changed. As for the dash issue, I have no idea. I didn't drive the vehicle today for fear I would get stranded at work, but I went out to check it when I got home and now the turn signal & high-beam indicators are off and I have backlights again. No fuses were blown. That's the first thing I checked yesterday. Anybody have any suggestions? You guys have been spot-on so far.
 

WhalePirot

Well-known member
Joined
May 9, 2002
Messages
2,942
Location
SoCA
Corvette
1984 White Z-51/ZF6-40/Shinoda body
Congrats on realizing your dream; sounds quite nice.

There is a gray two-pin weatherpak connector for each underhood lamp that may be dirty/corroded or unplugged. Follow the twin wires that are plastic clip routed from those lights to the space, forward of each front wheel well to find each. Those lights are a bit problematic.

A fuse check is always early on the list and with the new cars and all the electric gizmos, the connectors are crucial. I just fixed my left outside mirror's vertical movement by cleaning one of the (plugs) connectors inside the door. Electrical contact cleaner becomes an essential part of our normal toolkit.
 

1991-C4

Active member
Joined
Mar 13, 2010
Messages
25
Location
Wentzville, MO
Corvette
1991 C4
The first accessory item you should buy is the factory service manual. eBay is probably going to be your best bet on this. These have complete wiring diagrams that will help you trace what wire goes where. I was lucky and found a preliminary copy of the '91 manual and it actually cost more to ship it than the cost of the book! This is the manual that comes out during the design phase and should be "recycled" when the final version is published since there may have been some changes from the design to the production. But so far, I have not found anything inaccurate in my copy.
 

Jeff P

Active member
Joined
Feb 7, 2011
Messages
37
Location
Cheektowaga, NY
Corvette
2013 GS 60th AE
Hello All!

I just bought my dream car a few days ago! An '89 Dark Red Coupe w/ Black Leather Interior with just over 100K miles.

First, let me say that what I put in the subject line is true, although the headlights/parking lights/fog lights work perfectly. When I turn on the turn signals, left or right, neither cornering lamp comes on. Also, when the hood is raised, the underhood lamps don't illuminate. I thought these were supposed to come on as soon as the hood was opened, by way of a mercury switch, but I can't find it.

I already tried the most obvious by replacing the bulbs, but that didn't help. My next stop is the fuse block. If that isn't it, do any of you have any other ideas?
Seeing as it is an '89 and sooo many owners buy the aftermarket switch to manually turn them on and off (very useful when at a car show)...try seeing if there is a switch wired into the harness for them.....just a thought and good luck!
Jeff
 

DarkRed89Flyer

Active member
Joined
Mar 3, 2011
Messages
33
Location
Mesa, AZ
Corvette
1989 Dark Red Coupe
Congrats on realizing your dream; sounds quite nice.

There is a gray two-pin weatherpak connector for each underhood lamp that may be dirty/corroded or unplugged. Follow the twin wires that are plastic clip routed from those lights to the space, forward of each front wheel well to find each. Those lights are a bit problematic.

A fuse check is always early on the list and with the new cars and all the electric gizmos, the connectors are crucial. I just fixed my left outside mirror's vertical movement by cleaning one of the (plugs) connectors inside the door. Electrical contact cleaner becomes an essential part of our normal toolkit.

@ WhalePirot - You were correct! They were unplugged...

But, now, however, I have a different problem. I drove the car on a trip over the weekend. When I was getting ready to leave my home, I started the car right up, but it died almost immediately. After that, it wouldn't start. I tried 2 or 3 times and it wouldn't "catch." I finally did get it started after waiting about 10 minutes. On the way back home, yesterday, I stopped for a food/restroom break, and when I tried to leave, it wouldn't start. It would crank, but not fire off. In addition, the turn signal & high-beam indicators were on solid and the gauge cluster had no backlights. The headlights were not on. I'm thinking that my no-start issue is probably the need for a new fuel filter. It has 104K miles, and since I just bought it, I don't know if it has ever been changed.

As for the dash issue, I have no idea. I didn't drive the vehicle today for fear I would get stranded at work, but I went out to check it when I got home and now the turn signal & high-beam indicators are off and I have backlights again. No fuses were blown. That's the first thing I checked yesterday. Anybody have any suggestions? You guys have been spot-on so far.
 

vetteboy86

Well-known member
Joined
May 26, 2003
Messages
2,760
Location
IN
Corvette
1986 Black "Indy 500 Pace car replica"
Since this car is a new to you vehicle, and you're unaware of previous maintenance schedules, let's not assume anything. How familiar are you with working on cars?

We'll go from there. I would recommend the factory service manual, since it sounds like you will be keeping the car for a while. I would start by eliminating the easy things. While it sounds you may have potential electrical ground issues, start by trouble shooting by verifying proper fuel pressure.
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
@ WhalePirot - You were correct! They were unplugged...

But, now, however, I have a different problem. I drove the car on a trip over the weekend. When I was getting ready to leave my home, I started the car right up, but it died almost immediately. After that, it wouldn't start. I tried 2 or 3 times and it wouldn't "catch." I finally did get it started after waiting about 10 minutes. On the way back home, yesterday, I stopped for a food/restroom break, and when I tried to leave, it wouldn't start. It would crank, but not fire off. In addition, the turn signal & high-beam indicators were on solid and the gauge cluster had no backlights. The headlights were not on. I'm thinking that my no-start issue is probably the need for a new fuel filter. It has 104K miles, and since I just bought it, I don't know if it has ever been changed.

As for the dash issue, I have no idea. I didn't drive the vehicle today for fear I would get stranded at work, but I went out to check it when I got home and now the turn signal & high-beam indicators are off and I have backlights again. No fuses were blown. That's the first thing I checked yesterday. Anybody have any suggestions? You guys have been spot-on so far.

Before doing anything,. you need to read the ECM trouble codes.
Depending on whats there, you can do further testing. You're guessing until you know what the ECM knows. The engine may need a sensor, or it could be a security problem with a half-assed bypass....who knows.
You need to start collecting the basic tools for Corvette ownership...
Fuel pressure test gauge.
Noid lite
DVM (volt meter)
spark tester.
Paper clip.
Factory Service Manual set ($75 used @ E-Bay) DO NOT buy a cheesy haynes magazine-manual for $19<------useless.

The digital cluster is simple. High beam lite, both arrows on, everything else dark.....that is a broken/cracked ground terminal on a horizontal plug that hangs on the circuit board. Easy to solder and repair. If you don;t want to do it yourself, call 20th st auto parts in Phx and speak to Larry or Matt. They can fix you up with an exchange or a rebuild. Thats gonna be around $350 exchange.
 

DarkRed89Flyer

Active member
Joined
Mar 3, 2011
Messages
33
Location
Mesa, AZ
Corvette
1989 Dark Red Coupe
Since this car is a new to you vehicle, and you're unaware of previous maintenance schedules, let's not assume anything. How familiar are you with working on cars?

We'll go from there. I would recommend the factory service manual, since it sounds like you will be keeping the car for a while. I would start by eliminating the easy things. While it sounds you may have potential electrical ground issues, start by trouble shooting by verifying proper fuel pressure.

vetteboy86, I've been around cars/worked on cars since I was a child. Although, this is the first Corvette I've owned. I didn't see your post until just now, so I will check the fuel pressure the first chance I get. I'll let you know. If I haven't been misinformed, the pressure should be between 9 - 13 psi. Correct?
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
vetteboy86, I've been around cars/worked on cars since I was a child. Although, this is the first Corvette I've owned. I didn't see your post until just now, so I will check the fuel pressure the first chance I get. I'll let you know. If I haven't been misinformed, the pressure should be between 9 - 13 psi. Correct?

only if its a carb...or a crossfire

your 89 TPI requires around 40.
 

DarkRed89Flyer

Active member
Joined
Mar 3, 2011
Messages
33
Location
Mesa, AZ
Corvette
1989 Dark Red Coupe
only if its a carb...or a crossfire

your 89 TPI requires around 40.


I was misinformed! I'm glad I asked. I was able to check the pressure today and it hovers around 39 -40 only changing when the A/C compressor cycles while the engine is idling.
 

DarkRed89Flyer

Active member
Joined
Mar 3, 2011
Messages
33
Location
Mesa, AZ
Corvette
1989 Dark Red Coupe
Before doing anything,. you need to read the ECM trouble codes.
Depending on whats there, you can do further testing. You're guessing until you know what the ECM knows. The engine may need a sensor, or it could be a security problem with a half-assed bypass....who knows.
You need to start collecting the basic tools for Corvette ownership...
Fuel pressure test gauge.
Noid lite
DVM (volt meter)
spark tester.
Paper clip.
Factory Service Manual set ($75 used @ E-Bay) DO NOT buy a cheesy haynes magazine-manual for $19<------useless.

The digital cluster is simple. High beam lite, both arrows on, everything else dark.....that is a broken/cracked ground terminal on a horizontal plug that hangs on the circuit board. Easy to solder and repair. If you don;t want to do it yourself, call 20th st auto parts in Phx and speak to Larry or Matt. They can fix you up with an exchange or a rebuild. Thats gonna be around $350 exchange.

As a side note to my fuel pressure test mentioned earlier, I noticed that when I first attached the test gauge, there was no pressure at all. Is this normal when it has been sitting for several days without being driven? I might be under the wrong impression, but I thought the system was under some pressure all the time.

This is the first time I've had to "deal" with fuel injection systems...as for the ECM codes, none have been set.

I tried to do a search on e-bay for the Factory Service Manual and there aren't any for my year available at the moment. I'll definitely have to keep trying. In the meantime, I'll have to use the Chilton Book that came with the car.
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
As a side note to my fuel pressure test mentioned earlier, I noticed that when I first attached the test gauge, there was no pressure at all. Is this normal when it has been sitting for several days without being driven? I might be under the wrong impression, but I thought the system was under some pressure all the time.

This is the first time I've had to "deal" with fuel injection systems...as for the ECM codes, none have been set.

I tried to do a search on e-bay for the Factory Service Manual and there aren't any for my year available at the moment. I'll definitely have to keep trying. In the meantime, I'll have to use the Chilton Book that came with the car.

A good fuel system should hold near its full pressure for about nearly an hour then slowly drop (bleed down) to zero. Normal drop rate is around several hrs from 40 psi to zero. Some may drop faster..this indicates injectors leaking down and requires immediate service.
The fuel pump intake has a check valve to prevent back flow, but they do stick sometimes. new pump required.

Once you get some time, charge the system with pressure, and note the drop rate. Check it every 30 min until its almost gone.
It should only drop 2-3 lbs as soon as the key is turned off then loose maybe 5 per hr after. It should hold at least 20 for the first hr after shut down.

As far as the no start...next I'd pull the dist cover and look at all the wire contacts to the coil. If thats good, find a NOID lite to check inj pulse and a spark tester to see plugs fire.
 

DarkRed89Flyer

Active member
Joined
Mar 3, 2011
Messages
33
Location
Mesa, AZ
Corvette
1989 Dark Red Coupe
A good fuel system should hold near its full pressure for about nearly an hour then slowly drop (bleed down) to zero. Normal drop rate is around several hrs from 40 psi to zero. Some may drop faster..this indicates injectors leaking down and requires immediate service.
The fuel pump intake has a check valve to prevent back flow, but they do stick sometimes. new pump required.

Once you get some time, charge the system with pressure, and note the drop rate. Check it every 30 min until its almost gone.
It should only drop 2-3 lbs as soon as the key is turned off then loose maybe 5 per hr after. It should hold at least 20 for the first hr after shut down.

As far as the no start...next I'd pull the dist cover and look at all the wire contacts to the coil. If thats good, find a NOID lite to check inj pulse and a spark tester to see plugs fire.


Well, boomdriver, I have done a couple of the preliminary tests. I bought a spark tester and a set of NOID lights (a set of 6 different ones is the only way they sell them here at the local auto parts store). I did the "bleed down" test and after about an hour, the pressure was down to 26psi. I didn't get a chance to pull the distributor cap before it got dark, so I'll do that in the morning, but I did check the spark on each cylinder and that's OK. The curious thing is that while I was working on it today, I couldn't get it to not start. Each time I turned the key, it cranked right over. Each time, I wasn't in the driver's seat to touch the gas pedal, but a few days ago, I got stuck when I went to the store. I had to try to start it 6 or 7 times, before it would fire up. I was almost ready to call the tow truck!!! Tracking down an intermittent problem is ssooooo frustrating to me.
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
Well, boomdriver, I have done a couple of the preliminary tests. I bought a spark tester and a set of NOID lights (a set of 6 different ones is the only way they sell them here at the local auto parts store). I did the "bleed down" test and after about an hour, the pressure was down to 26psi. I didn't get a chance to pull the distributor cap before it got dark, so I'll do that in the morning, but I did check the spark on each cylinder and that's OK. The curious thing is that while I was working on it today, I couldn't get it to not start. Each time I turned the key, it cranked right over. Each time, I wasn't in the driver's seat to touch the gas pedal, but a few days ago, I got stuck when I went to the store. I had to try to start it 6 or 7 times, before it would fire up. I was almost ready to call the tow truck!!! Tracking down an intermittent problem is ssooooo frustrating to me.

Believe me, I know the feeling too well...

I had one that went on for months...
Everytime I went around a right hand corner under any power or over 10 mph the engine shut off for a second or 2....made me crazy. Go around a corner and it would completely cut out then jump back to life after the turn.
Finally found a loose wire to the distributer that was able to flop away when there was a little G-force in the right direction. I'd been looking at fuel tank baffles. I was in & out of that tank so much that I had my mail sent there..
and I could'nt understand why it went around left turns ok but not rights...I got tunnel vision aimed at the fuel tank and did'nt (could'nt) find the problem until I was doing another chore one day.

Keep the diagnosis brain storms simple. its either fuel OR spark. Just go thru one system a piece at a time until you get a result. The temptation is to do several things at once but that can be confusing IF you happen to solve the problem you may never know exactly what it was.
One step at a time. But DO find a reason, otherwise you'll never be fully confident in the car and that feeling sucks in a vette.
 

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