Starting problem with my '87.

[Ken]

I'll knock this back to the top again, in hopes of someone seeing it and being able to help with your problem. I can't help you (Yet - though I'm learning! )

 

[dr3283]

Thanks Ken. I'm in a learning mode too.....and having to learn more about this problem than I ever wanted to know.

 

[rockytoptilidie]

Also-please tell me what was causing Nige's problem? The ISS? Every 10-15 starts, my car decides it doesn't want to start. So I unhook the left battery cable for a few minutes, hook it back up, and it starts fine. What is causing this???

 

[Nige]

To: rockytoptilidie

Hiya!

I don't think that I ever managed to button down exactly what was causing the fault. I changed the starter motor, the battery and the starter motor switch (see Joel's posts).

I checked out the fuses, Park/Neutral switch, ignition barrel and VATS resistance module (unplugged the lead from the ignition barrel and bridged the connector with the relevant resistance).

I believe that it may have been a combination of things and I think that I have just found something else...

Having changed the starter and battery, for a couple of days the car would start immediately I turned the key. After that, it seemed to turn over for a long time before firing up. A couple of days ago, the same old fault came back!! All lights on, everything working, but nothing happening when the key is turned to start!

In deseperation, I used a set of jump-leads off of a friends car - and the 'Vette started like a dream!! The only difference was that I connected the positive lead to the battery and the negative lead directly to a bracket on the block.

I now think that I may have a damaged/loose earth connection somewhere - possibly the main one to the block (although I cannot seem to find where it attaches - any ideas?)

Since then, it hasn't happened again but I now carry a set of leads with me and if/when it happens again, I'm going to connect the negative terminal of the battery directly to the block and see if that cures it. If it does - problem solved! If not, I guess I'll be back here again asking for help!

I hope this helps.

Nige.

To be continued.........?

 

[dr3283]

SECURITY Light - Intermittent Starting

I've just replaced both the VATS fuse and the UTD fuse (behind the DIC in the dash) even though neither showed to be bad. The car has started fine with no failures for two full days......approx 20-30 times.
However, I still have a problem with the SECURITY light. It either flashes all the time or if I set the system, the light stays on constantly.....never goes off the way the manual indicates.
The only time the light ever goes off is when the car is actually running. The main problem here is that the battery is drained every couple of days unless I start the car.
Does anyone know which module controls the light......is it the UTD module or is it the VATS module? By replacing the module will this fix my problem?

 

[Nige]

To: dr3283

Hiya!

Frustrating isn't it? just when you think you've got the beast beaten, it comes right back at ya!

I have no idea what might be causing your problem but, during one of my (many) hunts for parts, I did notice an item that prevents undue battery drain when the car is not in use.

I think I saw it at Mid America Designs, but I'm not sure. Essentially what it seems to do is sit alongside your battery and if, when the car is switched off, it detects high drain, it prevents it somehow.

I know this is not going to solve your problem completely, but it might just save your battery!

Good luck!

Nige.

 

[rockytoptilidie]

My 86 has went a couple of days without the problem, and then all of a sudden, it will do nothing when I turn the key (yes, the lights come on, everything). Like I said in an earlier post-if I undo the negative cable for a few minutes, it always starts fine.

 

[dr3283]

Thanks Nige.....I'll check into that simply to keep from draining the battery 'til I hunt this monster down.
And by the way, Rockytilidies, I spoke too soon because just as you indicated, I went out this afternoon to try it one more time and it jumped up and bit me again. I tried unhooking a battery cable as you suggested with no luck......however, after re-reading your email you did say "negative" and I unhooked the positve. I'll try it again and let you know.
I have checked all my keys and they all have the "exact" same resistance values.....3740 ohms......next, I'll go to the bottom of the column and check the resistance there to be sure its the same.
I'm kinda interested in knowing what year models this problem affects. I've got 3 C4's (84, 87, and 95) and I've never "experienced" this before now. The 87 is my latest acquisition and I've had it for about a year before it started this nuisance.

 

[dr3283]

Rockytoptilidie......just wanted to let you know that disconnecting the negative cable on mine for a few minutes (about 5) had same effect as the positive cable......none. I've still got lights and gauges but it won't crank at all. I've got the dash back together but I'm going to open it back up, pull the fuse to the UTD again and see if it cranks like it did before. If so, I'm thinking that may isolate my problem to the UTD module. If not, I'll drop back 5 more yards and PUNT!
I'll start running down the list of ideas from Chick, Ken, Nige, and anyone else that has posted.

 

[rockytoptilidie]

I think it has been 3 days since I unhooked the battery. So anytime now, it should be cutting off.

 

[Nige]

Sorry Guys - I don't think I made myself properly clear...

Don't unhook the battery, just connect a second cable (preferably a battery jump lead) from the NEGATIVE terminal (VERY IMPORTANT THAT!) to somewhere on the engine block. (I connected to the big, solid bracket holding the alternator assembly in place.)

This has the effect of providing a proper negative/earth connection for the engine - bypassing the earth strap, which I understand is connected to the top of the gearbox (no wonder I couldn't find it!!)

The reason for this is to provide a good earth for the engine and, in particular, the starter motor - which pulls a large amount of power as it cranks over!

If the problem is down to a poor connection, this will overcome it and you can replace the temporary cable with a more permanent one, or get the original earth strap replaced.

Please note however, under no circumstances must the positive side of the battery be connected to the engine block - not unless your want 4th July - type fireworks!!

Hope this works for you.

Nige.

 

[dr3283]

OK guys......I'm back to square one. I've left it set overnight and it still won't crank this morning so I began back where I started.
I've checked the VATS fuse and its good. Both keys have 3740 ohms.....and when I check the connector at the bottom of the column as Ken or Chick or someone suggested, I got exactly 3740 oms there also......jiggling the key made no difference....it didn't change. I went ahead and ran to Radio Shack and got resistors that when hooked in series measured 3710ohms, hooked it to the end going to the module (not the switch) and still no start.

Next, I opened the dash back up and pulled the fuse to the UTD. (This let it start several days ago.) This time I got nothing. I did go ahead and check the fuse to be sure it was good.

I might mention again that I am still getting "weird" reaction from the SECURITY light. If the UTD fuse is in, it flashes continuously until you arm the system.....then it stays on solid. The only time it ever goes off is when the car is running. Not sure whether this is relative to the problem or just a "co-inky-dink".

This is my 12th Vette and I've never had anything more frustrating occur to any of these before......I'm reluctant to take this one anywhere for fear it will not start for days.......

By the way, I've checked the starter by bypassing everything and it cranks just fine. I've also checked the neutral safety switch and its fine too (checked continuity and then moved the switch position to be sure it would close the circuit.)

SO.......does anyone have any other "ideas"......do I replace the UTD module????? the VATS module????? the starter enable relay???? What about the ECM????? I kinda hate to just start replacing these....if they're not bad, it seems like it will just add another component that is gonna have to be checked out However, if thats the only approach, then I'll start. Does anyone know how if there is a way to check any of these components?
Thanks for all the responses so far. Every little bit helps.

 

[dr3283]

Vigman.....went back and did a search on all your input to the VATS problems to see what else I could do. I found your item that explains how to check the starter enable relay and I've got questions.

You indicate that there should be a Big Yellow wire in B and a Big Dark Green wire in C. I can't find any markings on mine but from inside the car I've got Big Yellow, Big Yellow, Small Dark Green, and Big Dark Green with white stripe. (Is my 87 auto different from the schematic you described?)

If I ground one end of my test light and turn the key to the start position, the second Big Yellow (I "assume" this is B) lights the light. So next, I bridged the Big Yellow (B) and the small Dark Green next to it (C???) and tried to crank it....I get nothin'.

Does this mean the starter enable relay is bad?????

I didn't try anything with the Green/White for fear I might short somethin' out if the schematic you described doesn't work for my car. (I sure don't need to add to my problems.....lol)

Thanks.

 

[vigman]

OUCH that was BAD

The BIG wires are the contactor to allow current to FLOW through down to the starter( via the clutch safe switch or auto tranny park/ neutral switch.

"So next, I bridged the Big Yellow (B) and the small Dark Green next to it (C???) and tried to crank it....I get nothin'."

The small dark green is the control line from the VATS.. I hope you didn't blow the transistor in the VATS

The small dark green line should GROUND when the vats is happy.

Try the following JUMP the two BIG wires and just BLIP the key. If the starter tries to turn the MAIN wiring is OK.

Then PUT the relay BACK.. ground the little green line.. does the relay go CLICK?

Get back to me on this.

Vig~

 

[dr3283]

Vigman.....thanks for the reply......oops.....hope I didn't blow the VATS....anything I can do to check that out before I proceed?

Before I go try this I want to be sure I understand.....when you say bridge the two BIG wires.....which 2......I've got the 2 Big Yellow (in Pin E and Pin C) plus a Big Green/White in Pin A. The small Dark Green is in Pin B.

I'm thinking you want me to bridge the Yellow in C and the Green/White in A but I want to be sure before I try anything else.

Sorry if I seem a bit slow here......I've been trying to be extra cautious and not cause any other problems......and after your last note I think I'm gonna hafta regroup.......lol

 

[vigman]

E & C are the same wire ( yellow's)

The splice is internal of the harness. They will both have +12 in the START position. Jump E to A ( Dark Green with white tracer)

This jump will BYPASS the contactor portion of the switch. Read BIG current.

Vig~

 

[vigman]

Pins C & D

Are the coil ( read control of the relay)

You have +12 in the start position ONLY from the Yellow wire... the LITTLE dark green in the ground ( control ) side of the relay.

IF the VATS is happy ( and the relay is working)... as you turn the key into START you SHOULD hear the relay CLICK.

You can try applying +12 on pin C and ground on pin D ( pull the relay out and bench test).

IF the relay goes CLICK.. now the circut between pin A & E should close ( make contact).

And there are NO silly, slow questions.


Vig~

 

[dr3283]

Vigman......still readin' all the notes on your other responses to other VATS issues. Saw where you explained how to check the ALDL connector to get the error codes from the CCM.

I haven't done this (didn't even have a clue how until I read this) and am wondering if I should do this next. Will this tell me where the problem is....in which module????

Looks like my ALDL connector is like the ODB style 1 you indicate however when I look inside the connector it looks like only 6 of the pins have connections in them. From sitting in the drivers seat looking into the connector, if the connections are marked as follows
F E D C B A
G H J K L M
Only pins A, B, C, E, F, and G have connections in them. The others are empty. Is this normal?????

If so, and I follow your directions, do I jump connection points A and G to get the readout?????

Thanks again.

 

[vigman]

A to B

G is the Fuel pump feed line.


Vig~

 

[vigman]

And the others empty..IS normal

For your year.


Vig~