dm_c4

Hello guys,

I have some electronic problem on my 1988 C4 and dont know any further about it

It suddenly occured and shows the following:

1. Anti-Lock control light is blinking while driving

2. Turn signals work when engine is idling and car stands still, but blinks very very slowly, about once every 3-5 sec.

3. When driving turn signals don't blink at all. When I stop the car then they do, again very very slowly.

4. When turning on headlights or pushing horn button while driving the engine starts to stutter. When engine idling I can turn on the lights without problems.

5. Fuel level shows full altough tank definitely not full. The shown range can be true (is not the range at full tank level).


So what could be the problem? Does anyone have an idea? Maybe the generator is broken? Or some elec. short? But where?

I have no idea.

Thanks so much for any help!

antfarmer2

I would start by testing your battery and alt and clean all connections.

dm_c4

Thank you
Yes maybe I should start with this. Seems like no one has an idea anyway

N42375

I agree with Antfarmer. The problems you describe would indicate a voltage fluctuation. Low voltage would cause the directional signals to blink slowly. Do a load test on the battery,then check the voltage output at the alternator and then the voltage regulator. Don't overlook your ground wires. Corroded wires can really have you chasing your tail to find the problem.

dm_c4

Today I spend some time about it but couldn't get any further.

1. I installed another battery and checked all connections to the battery -> problems persist

2. checked battery/ alternator following this instruction: http://www.rockauto.com/Newsletter/a....html#tomStory

-> not really a result

-batt has 12,4V
-with engine running 14,8V
-enigne off and ignition on 11,90V

3. adding a 2nd batt with jump start cable OR my other car (has 110amp batt) -> no change

When engine off turn signals are blinking veeeeery slowly, when turning on head lights turn signals nearly stop blinking.

The only thing was that when I added another batt with jump start cable then the fuel level shows correctly (reserve) instead of full.

So I have no idea. If there is some short cut where should I start? There are probably hundreds of cables on the car. But where can come a short cut from when the car is sitting around?

Any further help is very much appreciated! I am totally clueless

mickey5

Sounds like a corroded ground. Dampness is your enemy.

dm_c4

Hi mickey5, do you think of a specific wire that I should check? There is one ground cable that goes directly from battery minus pole to the frame. Maybe I should renew it and look if this helps

dm_c4

And one question about the voltage regulator.

Is this inside the alternator? Could it be the reason also if the descibed problems occur when engine is NOT running?

What are these boxes behind the battery? (shown in this pic http://s1207.photobucket.com/user/wa...l?t=1378503641 )

ctmccloskey

Hello there,
I have a 1988 C4 coupe and it sat for a while. After trying to wake it up I found a huge number of issues and most of them were electrical.

Being a Battery specialist I would right away say that 11.9 with ignition on sounds really low. Your open circuit voltage looks okay but I would strongly suggest that you charge this battery up with a minimum 15 amp rate just to give it a good equalizing charge. Batteries that sit around can sometimes develop stratified electrolyte. When the electrolyte gets stratified it will appear to have a good battery when you only have a fraction of its capacity. A good solid charge will usually take care of it for you. Now, on to the fun part....

I would get a multi meter and start looking to be sure that your grounding system is working properly. With the car "off" try this. Holding the ground wire from the meter (black) on the battery (-) negative terminal take the red positive (+) wire from the meter and read the voltage at the output terminal on the alternator. You should get the exact reading that you got when you tested the battery by itself. You should see full battery voltage.

Then with the meters red wire connected to the positive (+) side of the battery connect the ground wire to the engine block on solid metal. When you do this you should also see full battery voltage.
These tests are the very first I would perform before diving into anything.

Behind the battery is a post with several wires connected to it. This is where the battery supplies power into the (most of the) rest of the car. Remove the terminals and clean each one of the ring terminals so they are nice and shiny. Using a tiny pin and my meter I verified that each of the fusible links were good.

In my case the corrosion was the absolute worst at my fuse block, it appeared okay to the naked eye but my fuses were not conducting any current. I removed all the fuses and replaced them. They all still had the internal wire intact but they did not conduct any electricity, weird.
So after using Electrical terminal cleaner with a small file (old points file worked great!) or a piece of Emory cloth I cleaned every connection and the fuse holder blades. Some of my fuses had a white residue on it like aluminum corrosion and it was found in the fuse block as well. After installing new fuses the car suddenly woke up and where there was no power before I now had 12 volts. I replaced the circuit breakers as well, just to be safe.
It appeared that water (or lots of moisture) had got into the fuse block area somehow and started most of my troubles. Check for voltages at the fuse block to see if you have the same problem.

I bought a tool which I have found to be "The Tool" when I am trying to solve problems like yours. It is called a "Power Probe IV" and it should be included in every Corvette owners tool box. it will help you find and solve all the electrical gremlins that we deal with. You can get an older model for less but the Power Probe IV has features to resolve complex Fuel Injection issues as well as finding the bad grounds for you. It lets you test each fuel injector and so much more. The cost at Amazon is about $135 complete, worth every penny.

Let us know what happens when you finish these tests, you got my curiosity going.

Best Regards and the Best of Luck!

dm_c4

Wow thank you so much for this detailed answer!!

I will try this an let you know what I found out.

mickey5

You never indicated how well the starter turns over the motor.

Here at the Jersey Shore after hurricane Sandy, 1000's of cars were flooded with sea water. As the months passed these cars started to exhibit various electrical problems as the sea water residue corroded every contact. I mention this because we found that the wire itself corroded at the mechanical terminations. Check the battery cables themselves to make sure they're in good condition.

Good luck with your hunt.

dm_c4

Oh sorry if I forgot to mention. The engine starts right up and cranks like normal, there is no weakness or so. That's also why I think that it probably should not be the battery.

mickey5

Since the motor spins over with little hesitation and several features of the car were all affected at once I would checking out the fuse panel as Mc Closkey noted in his response.

dm_c4

Can someone please tell me what these black things are that are on some of the cables (see picture)? There is e.g. a 20 on it. Is this some fuse or just a cable connector or so? You cannot open them.

dm_c4

Well so far I was not successful

I replaced the battery, replaced the battery connectors, checked all cables I could find, replaced some that did not look so good, loosened all endings and cleaned them with anti rust and contact spray, replaced all fuses. All that changed nothing.

Well now I think I will order a new alternator or what do you think?

If this would not solve it neither the only other idea I have is to completely new wire all the lights and blinkers separately so that they don't interfere the car's electrics.

Or any other ideas or suggestions? Thanks for helping!

mickey5

Don't waste your money on an alternator. If its putting out 14+ volts its doing the job. To verify, take it off and take it to a rebuilder. They've got everything needed to spin it up and ckeck it out. Takes a couple of minutes and maybe a couple of bucks...maybe nothing.

dm_c4

Well yes I am afraid that this will be waste of money, too
I just have the idea that I will take the bulbs out of the headlights and will test if the engine still starts to stutter when I turn them on. So I could see if it is a lack of voltage or a short circuit. Just an idea...

Cliff Harris

That is a wire splice that connects the fusible link to the standard type of wire. It is covered with molded plastic to keep it from shorting to whatever.

dm_c4

HI, thank you so much for this great approach. Excuse me please if I'm not that expert, so can you please clarify some questions to me?

1. Do I get this right that it could be an issue with the ignition switch that causes the trouble?

2. The readings on the battery I do also take when the engine is running, right?

3. What is the B+ wire?

4. The TAIL fuse is the one for the headlights, right?

5. Do I take the fuse of the circuit that I test our or let it in the socket?

Thanks for helping

dm_c4

Well today I finally did the checks.

I checked for fuses CLK, Tail, LCD, Brake and got the following 'table':

__________Headlight off ____ Headlight on

Batt+ ______ 12,4 ___________ 12,3

CLK, Tail ____ 12,3 ___________ 11,9
LCD, Brake __ 12,4 ___________ 12,12

This is for engine off. When engine is running then it's all something with 14,x Volts but the same differences.

So how does that help me now?

Thanks