Bypassing the clutch switch

[StickWalker]

To bypass the clutch swith do I just take the thick yellow and purple wire out of this harness and splice them together??
http://i134.photobucket.com/albums/q115/lgaff/DSCN5277.jpg
I thought I could just wire the white connector thats hanging down together and that would do it. Keep in mind I am color blind and having the typical No Crank issue with a fully charged battery. Any help would be appreciated.
http://i134.photobucket.com/albums/q115/lgaff/DSCN5278.jpg
http://i134.photobucket.com/albums/q115/lgaff/DSCN5280.jpg
I borrowed these pics from LGAFF and it looks like he just cut the yellow and purple wire out of the connector and spliced them together.. is that all it takes?
Don

[LGAFF]

Yup, change your relays while you are in there too

[StickWalker]

LGAFF, thanks for the quick reply. What does the white connector hanging down do then, because it looks like it has a plunger that tells when he clutch is pressed as well.

Don

[LGAFF]

cruise control switch, turns cruise off when you depress the clutch

[StickWalker]

LGAFF, turned the key and she fired right up!!! Thanks for the confirmation for the color impaired!

Don

[LGAFF]

Now just be sure to press the clutch in whenever you start it....there are relays below the steering wheel you may want to change, one of those will sometimes also stop the car from starting when its bad

[LGAFF]

The actual relays are facing the firewall....the backside of the relay box is what you will see facign you. You must reach around the back to pull them...

[StickWalker]

Yup, I saw them.. barely, but I can see them.. and I have never owned and automatic, so my foot is always on the clutch at start up, with Emergency brake on.. just the way I was taught

[LGAFF]

http://i171.photobucket.com/albums/u309/vetteoz/electrical/RelaysC4Late.jpg (http://api.viglink.com/api/click?format=go&key=5e9e33f20bf41d5a669cc4838c2690e9&loc=http%3A%2F%2Fforums.corvetteforum.com%2Fc4-tech-performance%2F2697354-starter-relay-location.html&v=1&libId=525643d2-b031-4238-a8cd-148cd714116d&out=http%3A%2F%2Fi171.photobucket.com%2Falbums%2Fu 309%2Fvetteoz%2Felectrical%2FRelaysC4Late.jpg&ref=http%3A%2F%2Fwww.bing.com%2Fsearch%3Fq%3Dstart er%2Brelay%253B%2Bc4%2Bcorvette%26src%3DIE-SearchBox%26Form%3DIE8SRC&title=starter%20relay%20location%3F%3F%20-%20Corvette%20Forum&txt=&jsonp=vglnk_jsonp_13817595566098)

[LGAFF]

Figure 24 starter enable relay, mine was bad also

[max76]

Hi guys...after bypass the clutch switch is better change the starter enable relay?
how i can check if it's good or not?
Thanks in advance!!!
Max

[Paul Workman]

In ALL ZR-1s the clutch relay carries all the current drawn by the starter solenoid - a few amps. However, only on the 90-92s does the clutch switch carry the entire current to operate the starter solenoid. On the 93-95s the clutch switch enables the clutch relay (via the CCM), thus reducing the amperage load and the arching that erodes the clutch switch contact points (only) significantly.

So, it might be a good idea to have a clutch start relay (and possibly some others too) in the glove box, along with an assortment of fuses too, just in case.

90-92 Clutch schematic(1)

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/90-92starter_zps9170e748.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/90-92starter_zps9170e748.jpg.html)

93-95 Clutch scematic(1)


http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/95starterviaHaibeck_zps4f96d5a3.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/95starterviaHaibeck_zps4f96d5a3.jpg.html)

On this topic, Scottfab pointed out that arching can be reduced in the clutch switch IF the clutch is fully engaged before, during, and after the starter is engaged vs. turning the switch to START and then engaging the clutch switch...especially on a 90-92 car.

Although the clutch switch is redundant to those of us taught to engage the clutch first any time the starter is engaged, I think it is important to have it in working order as a hedge against the unexpected - who knows what!?

Essentially converting the clutch switch to the role played by the 93-95 cars is accomplished in a 90-92 car by installing a relay between the clutch switch and the starter solenoid. This way the relatively large solenoid current is isolated from both the start relay and the clutch switch - truly a mod worth considering to improve reliability of both the clutch relay (all cars) and the clutch switch in 90-92 cars.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/StarterRelay_zps748153c8.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/StarterRelay_zps748153c8.jpg.html)

Locating this relay near the fused link post (under the battery) provides a convenient location to access battery power for the starter solenoid path through the new relay. And, installing its own socket for the new relay allows for quick replacement, should it be needed.

Paul
___________

ref:
(1) Marc Haibeck article posted in HOTB.

[max76]

Hi Paul...thanks for picture's!!!
I have bypassed the clutch switch and the VATS.
What can i do to resolve the problem?
Ok, i'll change the starter enable relay, there are other relays need to be change?
I also understand the car need an other relays (clutch start relay), but i don't understand how to connect it....
Thanks in advance
Max

[Dynomite]

Locating this relay near the fused link post (under the battery) provides a convenient location to access battery power for the starter solenoid path through the new relay. And, installing its own socket for the new relay allows for quick replacement, should it be needed.

Paul
___________

ref:
(1) Marc Haibeck article posted in HOTB.

On the Early 1990s the wire to cut is RED (there is no 12 gauge purple wire)

Starter Relay, Wiring Harness, and Plugs Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-3.html#post1581564085)

I locate the Relay UNDER the ECM which is right next to the wire harness/wire to be cut.

60 / 80 AMP RELAY SPDT SINGLE POLE DOUBLE THROW NEW 654
Installed under ECM and in slot between brake booster and fire wall (perfect place for location of Relay).

Wiring modified a bit to assure Pin #87a is not hot at any time.
Pin #30: Purple wire to starter (use 3/8 inch connector on relay).
Pin #87: Red wire battery positive 12v use 3/8 inch connector on relay (connected to battery positive multiple connection post).
Pin #86: Battery ground (1/4 inch connector on relay connected to ground where battery 12 gauge wire grounded).
Pin #85: Purple wire from ECM use 1/4 inch connector on relay (Red wire on early 1990 ZR-1).
Pin #87a: Not hot at any time and not used.

http://i287.photobucket.com/albums/ll142/dynomite007/LT5/Relay-1.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/LT5/StarterRelay.jpg

Insert a short 1/2 inch long section of plastic hose
over the center connector on the Relay which is NOT
used in this application.
http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite7/6a0cf152-cb82-46e7-88aa-3321643f629b.jpg

[Paul Workman]

Thanks, Cliff for that added info.

[max76]

Dynomite, under the driver side panel i used purple wire to bypass clutch switch...and the purple wire go to the starter...
So, in your picture there is the clutch pedal switch, i haven't that anymore, i can do it anyway?

[Dynomite]

Dynomite, under the driver side panel i used purple wire to bypass clutch switch...and the purple wire go to the starter...
So, in your picture there is the clutch pedal switch, i haven't that anymore, i can do it anyway?

For installation of the relay next to the Wire Harness under the ECM....cut the Purple wire in the harness (leaving a lengh of purple wire going to starter) and add a short length to the end of that purple wire coming from the ECM. That wire then connects to the 1/4 inch connector on the Relay......The center connector on that relay is NOT used.

The other end of the purple wire going to starter you connect to the Relay with a 3/8 inch connector.

But not to worry....I am going out in an hour to redo my Relay (I want to use my new heat gun on that purple wire splice shrink tube which heat gun I did not have the other day). I will take photos of the whole installation for you showing the connectors. Just hang in there ;)

I have this same modification on three 1990s and one 1991 and they ALL function perfectly.

[max76]

DYNOMITE:


Wiring modified a bit to assure Pin #87a is not hot at any time.

Pin #30: Purple wire to starter (use 3/8 inch connector on relay).
This is the purple wire to the starter

Pin #87: Red wire battery positive 12v use 3/8 inch connector on relay (connected to battery positive multiple connection post).
There is a place where find a multiple connection? where is located?

Pin #86: Battery ground (1/4 inch connector on relay connected to ground where battery 12 gauge wire grounded).

Pin #85: Purple wire from ECM use 1/4 inch connector on relay (Red wire on early 1990 ZR-1).
I must disconnect the red wire from the ecm and connect it to pin #85?

Pin #87a: Not hot at any time and not used.

[max76]

For installation of the relay next to the Wire Harness under the ECM....cut the Purple wire in the harness (leaving a lengh of purple wire going to starter) and add a short length to the end of that purple wire coming from the ECM. That wire then connects to the 1/4 inch connector on the Relay......The center connector on that relay is NOT used.

The other end of the purple wire going to starter you connect to the Relay with a 3/8 inch connector.

But not to worry....I am going out in an hour to redo my Relay (I want to use my new heat gun on that purple wire splice shrink tube which heat gun I did not have the other day). I will take photos of the whole installation for you showing the connectors. Just hang in there ;)

I have this same modification on three 1990s and one 1991 and they ALL function perfectly.



Thank you so much!!!!!!:handshak::handshak::handshak::handshak: :handshak:

[max76]

Dynomite,
when i put the new relay the old one still works?

[Paul Workman]

Dynomite,
when i put the new relay the old one still works?

Jumping in...

Yes - referring to the existing START relay - still is in the circuit, except on a 90-92 the current load is drastically reduced, improving the reliability of that relay (and the clutch switch too, for those choosing not to bypass it).

Looking forward to Dyno's pix too.

P.

[max76]

Ok Paul, thank you
Yes we are waiting dynamite picture's...these are the most important pic's...
The new relay is 60-80 ampere?
Here, on ebay.it i saw only 40ampere relay...i hope are there in local dealer...

[max76]

Ok dynomite, i'll take the picture and in these days i'll go to the local dealer to buy it...
so, i can change the original relay because i think it's cooked!!!!!

[LGAFF]

http://www.zr1.net/forum/showthread.php?t=20411&highlight=start&page=2

[Dynomite]

Look at this on eBay:

http://pages.ebay.com/link/?nav=item.view&alt=web&id=110373059322

60 / 80 AMP RELAY SPDT SINGLE POLE DOUBLE THROW NEW 654

Since this thread is about bypassing the clutch switch I will explain step by step details of the Starter Relay Installation in a separate thread.

I have had several types of No Starts in 1991s and 1990s and the Starter Relay in conjunction with Starter Solenoid Restoration cured them all.
See item #2 Electrical Ground Connections and Installing Starter Relay (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-3.html#post1581564089) ;)

See also Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-3.html#post1581564085)

Keep in mind the starter Solenoid wiring in this very early 1990 is 12 gauge red (NOT PURPLE) which is rare.

[max76]

Thank you so much!!!!!!!!!!
Great job dynomite!!!!!
So, with this modify the starter enable relay work better? Could be "fresh"...really?
Ok...in the next day i'll try to do the modify...but i think have the purple wire and not the red one....under the dash when i bypass the clutch switch i connect the yellow and purple wire, like in the paint of first page.

[Paul Workman]

Thank you so much!!!!!!!!!!
Great job dynomite!!!!!
So, with this modify the starter enable relay work better? Could be "fresh"...really?
Ok...in the next day i'll try to do the modify...but i think have the purple wire and not the red one....under the dash when i bypass the clutch switch i connect the yellow and purple wire, like in the paint of first page.

I guess I'm not understanding the point of installing the additional relay if you are bypassing the clutch switch, UNLESS the existing START relay is difficult to get to (I don't know). Adding the new relay will simply transfer the heavy current chores to the new relay, which would be good, but ONLY IF getting to the START relay is more difficult than removing the battery and changing the modification relay - that I don't know (haven't tried to replace it).

[max76]

I already bypassed the clutch switch about 2 years ago...

The new relay location is under the ecm...sorry but i don't understand what you are saying

[Paul Workman]

I already bypassed the clutch switch about 2 years ago...

The new relay location is under the ecm...sorry but i don't understand what you are saying

If you install the new relay circuit as I designed it,

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/StarterRelay_zps748153c8.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/StarterRelay_zps748153c8.jpg.html)

the load on BOTH the existing START relay and the CLUTCH SWITCH is effectively transferred to the new relay without loosing any of the safety features! But, if you take the CLUTCH SWITCH out (by-passing it), you loose the safety feature and end up with a redundant relay (two in series).

The the question is: Without the CLUTCH SWITCH, is installing another relay justified?? Will the effort to install the new relay and then access it again later to replace it if need be, compared to simply replacing the original START relay justify the effort and expense of installing and maintaining the new relay??

I've never changed the original START relay, so I don't know what it would take to change one out. However, I intend to retain the safety feature afforded by the CLUTCH SWITCH, and so the auxiliary relay makes sense...maybe.

AND, as I said, a really good point made some time ago by Scottfab was you can eliminate all of the damaging arching in the CLUTCH SWITCH - even in the 90-92 cars IF you fully engage the clutch before turning the START switch, followed by releasing the START switch BEFORE releasing the clutch. That way the switch contacts are fully engaged before the high current load is applied, and the load is gone before the contacts are broken. (With this in mind, I'm less inclined to install that relay myself. But, rather have a spare START relay in the glove box...just in case.)

And, another thing: I'd rather go solid state whenever possible, as opposed to mechanical relays. And, I'm sure if someone wanted to use a FET transistor(s) for the switch instead of the auxiliary relay, it wouldn't be too difficult.;)

[max76]

Ok Paul....
So, before i install the second relay i want check the old relay and see (if it's possible) if internal components are damaged.
If they are damaged, first thing is change the old relay (obviously)...so, maybe the problem is only that.
This saturday i think to have just a little time to remove the protection and look the old relay conditions. I also can restore the clutch switch...
Someone, here in Italy, say to install a push button (temporary) to connect directly the battery with the starter, this in case i have te same problem, i can try if the problem is the relay or the starter...
Could be a different solution?

[Paul Workman]

Ok Paul....
So, before i install the second relay i want check the old relay and see (if it's possible) if internal components are damaged.
If they are damaged, first thing is change the old relay (obviously)...so, maybe the problem is only that.
This saturday i think to have just a little time to remove the protection and look the old relay conditions. I also can restore the clutch switch...
Someone, here in Italy, say to install a push button (temporary) to connect directly the battery with the starter, this in case i have te same problem, i can try if the problem is the relay or the starter...
Could be a different solution?

I don't know if you can open the old START relay to inspect it w/o destroying it. OR, once you've removed it, would it not make sense to just replace it with a new one and not worry about the old one.

A push-button solution, making a direct battery to starter connection, as a back-up, could work.

And, then there's the starter solenoid contacts - which can also become worn out - arching again - nothing you can do about that except replace the burnt posts and solenoid armature/contact ring (or recondition the copper contact ring with some sand paper (is what I did).

[max76]

The first thing i'll do is replace the starter enabled relay, once i have the new one i'll try to open the old one, just for curiosity...

Yes, the push-button is to check (when happens) if the problem is the relay or the starter.

Last year, when i change the injector i replace also the copper contact into the starter, new ones and with little more thickness.
Now, there are some other things could be bad into the starter?
There are modification required on the starter?

[Paul Workman]

The first thing i'll do is replace the starter enabled relay, once i have the new one i'll try to open the old one, just for curiosity...

Yes, the push-button is to check (when happens) if the problem is the relay or the starter.

Last year, when i change the injector i replace also the copper contact into the starter, new ones and with little more thickness.
Now, there are some other things could be bad into the starter?
There are modification required on the starter?

Far as your questions regarding the starter, I've replaced the electrical contacts, but as for any other aspects regarding failures, I would refer you to Marc Haibeck (http://zr1specialist.com/)who has seen many more starters than I ever hope to!

[Dynomite]

Paul.....what is the Bold Red Line? I am assuming that depicts the current path through the relay we install without showing the relay?
Nice diagram.....:thumbsup:
thanks,
Cliff


90-92 Clutch schematic(1)

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/90-92starter_zps9170e748.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/90-92starter_zps9170e748.jpg.html)
Paul
___________

ref:
(1) Marc Haibeck article posted in HOTB.

If it were not for the fact the LT5 starter is buried deep under the Plenum, refurbishing the starter Solenoid would be a piece of cake.

Starter Contacts.
The Starter Solenoid is shown in the left photo with slight burnt contacts in right photo.
http://i287.photobucket.com/albums/ll142/dynomite007/Maintenance%20ZR1/bac49725-6086-4f07-a929-9f1f498e4d50.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Maintenance%20ZR1/e8886408-e5b8-40d3-a5d2-199e22f85e0a.jpg
The Solenoid contacts in left photo were wire brushed clean in right photo.
http://i287.photobucket.com/albums/ll142/dynomite007/Maintenance%20ZR1/95a2d94c-6e14-4206-ab39-e157c17fc6a2.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Maintenance%20ZR1/e6b04516-3ebb-49ab-9f32-1da552901435.jpg

[max76]

Hi guys, i don't understand a thing...in the 93/95 schematic, where is the second relay?
If i well understand put the second relay in 90/92 cars is to update the circuit like the most new ones...it's correct?

[Paul Workman]

Hi guys, i don't understand a thing...in the 93/95 schematic, where is the second relay?
If i well understand put the second relay in 90/92 cars is to update the circuit like the most new ones...it's correct?

Ah, My bad. I should have explained the schematics show the stock setup in the 90-92 and the 93-95. (Schematics from an article by Marc Haibeck appearing in the HOTB related to "NO START".)

The additional relay (not pictured) is inserted between the CLUTCH SWITCH and the STARTER on the 90-92 schematic. (On the 93-95 there is little reason to install the additional relay, unless the factory START RELAY is so difficult to get to [I don't know] that it justifies installing the axillary - simply to move the high current switching to a more convenient location.)

And Cliff, the RED line is the high current path. The GREEN line on the 93-95 schematic is the low current "signal path" showing how the CLUTCH SWITCH is isolated from the high current path; a marked improvement, methinks.

Hope this helps clear things up. :o

[Dynomite]

What is the input and function of the starter enable in the Central Control Module (90-92)?
The CCM function activates the Starter Enable Relay (90-92)?

Then we have the higher current load passing through the Clutch Start Switch (90-92) which we reduce that current load using an additional Relay which provides a much shorter and unencumbered path between the Battery and Starter Solenoid.

On the 90-92 we eliminate the ignition switch path between the battery and Starter Solenoid as well using the New Relay.
If we installed the New Relay on the 93-95 we would be using direct current between Battery and Starter Solenoid not relying on current passing through the Ignition Switch (in that regard the same benefit as on a 90-92).

[max76]

Sorry...what is HOTB????
Thanks

[Paul Workman]

Sorry...what is HOTB????
Thanks

Sorry. :o HOTB (aka "Heart Of The Beast) is a periodical magazine available to ZR-1 NetRegistry members only (on line). No matter, far as this discussion is concerned, as I lifted the pertinent schematics from that article for this discussion - but do credit the schematics to the author (Marc).

[carnold]

Looking for a start cure. I have a 90 ZR1 and for years it starts fine but after I stop and leave it for an hour or so and come back I push in the clutch, turn the key, all proper lights come on but starter will not turn over. I leave it for 2 or 3 hours and it will then start fine. I bypassed the VATS system but still have the problem. Is it the clutch switch or the starter relay or something else. It is a 3700 mile car.

[Dynomite]

Looking for a start cure. I have a 90 ZR1 and for years it starts fine but after I stop and leave it for an hour or so and come back I push in the clutch, turn the key, all proper lights come on but starter will not turn over. I leave it for 2 or 3 hours and it will then start fine. I bypassed the VATS system but still have the problem. Is it the clutch switch or the starter relay or something else. It is a 3700 mile car.
Does the starter solenoid move and no start or solenoid sticky?

Do lights dim when you turn key to start?

I always install the Starter Relay and along with that always recondition the starter solenoid and points (and check armature bearings for smoothness and starter Brushes).

[carnold]

Lights do not dim. Solenoid does not click. It acts just like a VATS problem but it has been bypassed.

[Dynomite]

Lights do not dim. Solenoid does not click. It acts just like a VATS problem but it has been bypassed.

It sounds to me like the starter solenoid is sticky after heating up and has to cool down to activate. Assuming your battery is fully charged. The other items that may cause your starter issue have nothing in common with the engine temperature as far as I know.

I assume you installed the Starter Relay taking direct current from battery to Starter Solenoid when activated by a lower required current to activate the Relay itself through the Clutch Switch.

[carnold]

No have not touched clutch switch or added relay. It is bone stock. I am to old to be removing battery boxes and adding another relay. Could it be the clutch switch or original relay?

[Dynomite]

No have not touched clutch switch or added relay. It is bone stock. I am to old to be removing battery boxes and adding another relay. Could it be the clutch switch or original relay?

It could be....since when engine warm may take a bit more current to move the Solenoid and as such may be beyond the capability of the clutch switch to handle that current. In other words you have less voltage at the Starter Solenoid because of the greater resistance in the Clutch Switch Circuit at a time when the Solenoid takes a bit more voltage to function when engine warm.

[carnold]

Think for a start it would do any good to bypass the switch?

[Dynomite]

Think for a start it would do any good to bypass the switch?

It is worth a try and would help diagnose the situation.......that would eliminate (at least for now) the switch as the culprit if in fact it still does not start. If it starts that would point to the switch as the item having excessive resistance in the start circuit providing voltage/current to the starter Solenoid (which may be a bit of a culprit being sticky and requiring more voltage (greater magnetic field) to activate).

[carnold]

Thanks will give it a try.