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91 DeVille will not crank


K5JMP

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Hi all, new member here with a couple of questions...

First, let me preface this with a little history. My father was killed in a head-on on Feb 12. I arrived in Texas to find my mother's caddy inop. Needless to say the suburban was destroyed in the accident, so I need to repair mom's caddy for transportation.

Anyway, I am seeing no cranking voltage at the solenoid... I have worked my way back through the circuit and have hit a stumbling block as to exactly which relay is the starter interrupt relay. The Haynes manual blows... tries to cover way too many models and is pretty much useless. My time here is growing short before I have to go back home. Been here almost 3 weeks, and vacation time is gone....

If anyone has a service manual with the relay locations and the correct wiring diagram I would certainly appreciate the help. I am located in Tyler, Texas if anyone is close by and can help pop my head outta my hiney on this one..

TIA!! Mike

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First I am sorry to hear about your dad, that is terrible, I wish you and your mom well..

Does the POWER cable on the starter have power?, its the heavy wire..

Check your battery connections for corrosion. Do you hear any clicking? Does the dash come on? Lights and horn?

Please provide more details..

Check for codes, maybe your security system is killing the start circuit, here is how to check codes (press and hold the OFF and WARMER) and write down the codes that come up (assuming you have any power at all), post the codes here..

post-2998-1172797289.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Very sorry to hear that your Father died.

I have a 1992 Eldorado/Seville shop manual, but not Deville, and I am in Plano about 108 miles NW, from Tyler.

For the starter enable relay the shop manual says for the Eldorado/Seville :

1) lift cover from rocker channel

2) starter enable relay

There is a small picture, but it is not much help in telling where on the car they mean. Based on the reference to a rocker channel, I would guess the relay is on the bottom, along the side of the car. Not sure if it is in a similar location on the Deville.

Bruce

2016 Cadillac ATS-V gray/black

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Thanks for the kind words... it is a very trying time, but we have to move forward. Just really weird not having dad around to talk to. I have caught myself reaching for the cellphone many times over the last couple of weeks

I am a pretty fair hack and wrench-bender, but not at all famaliar with this car... also very minimal tools here... dad's foreman ripped-off most everything from his business within hours of his death. So tools are pretty much nil. I am an electrical engineer by trade and an 'ol-skool dragracer for about 30 yrs now... my normal hang-out is either the Vette forums or nastyz28.com

Everything appears to be normal, except no signal to solenoid. All gauges and dashlights appear normal... The underdash relays on the right hand side click when I turn the key to the start position.. just no crank. I used a screwdriver to jump the solenoid and check for spark while cranking and fuel pressure is good. Just no crank signal.... I have also checked the nuetral saftey start switch... so it has to be upstream from there.

I was concerned that it might be the VATS system (not sure what it is called on a caddy). I just don't have much in the way of resources here so I thought I would check the on-line forums.

I will give the error codes a shot first thing tomorrow afternoon.... just didn't recall how to invoke the code display... Gotta run to Dallas in the morning to file a life insurance claim.

thanks,

mike

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I think if the Security system engages you will get a message on the DIC, something like STARTER DISABLED, I will pull out my manual later. Try using some WD40 on the KEY and resistor and work it in and out to try to clean the contacts if you think its the security system..

I will look through my 91 manual, is this a 4.9 in the Deville?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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First I am sorry to hear about your dad, that is terrible, I wish you and your mom well..

Does the POWER cable on the starter have power?, its the heavy wire..

Check your battery connections for corrosion. Do you hear any clicking? Does the dash come on? Lights and horn?

Please provide more details..

Check for codes, maybe your security system is killing the start circuit, here is how to check codes (press and hold the OFF and WARMER) and write down the codes that come up (assuming you have any power at all), post the codes here..

I think if the Security system engages you will get a message on the DIC, something like STARTER DISABLED, I will pull out my manual later. Try using some WD40 on the KEY and resistor and work it in and out to try to clean the contacts if you think its the security system..

I will look through my 91 manual, is this a 4.9 in the Deville?

Everything electrical appears to be functioning.. except for the starter. Starter has been replaced and cranks when you bridge the bat and start terminals on the solenoid...

OK.. I tried the codes display and get nothing but 3 dashes... The car has not been started since I replaced the battery. Dad left it discharged and the battery was toast so I replaced it. It would appear that there are no codes stored. I did try using electronic contact cleaner on the ignition switch to no avail...

mike

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How about the ignition switch on the column? Not the tumbler, but the switch that the tumbler is connected to via an actuator rod.

I haven't gotten that far as of yet... but it was on my list. I gotta pick-up a small set of tools to drop the column to get to the switch if I recall correctly... at present all I have for tools is a Gerber wire-man's tool from the Army, knife, pliers, etc in a folding handle. Gonna fix that in the morning. Honestly, this is the first chance I have had to look at it... been trying to save a business and get death certificates, insurance ... all ducks in a row so mom has some income.

Thanks for jumping in guys... I do appreceiate the direction.

One other thing... call your folks and let them know you love 'em. Things can change pretty quickly....

mike

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Just like everybody I am sorry to hear about your father.

You can cut some corners by running a jumper from the battery positive terminal to the solenoid positive. That way you'll bypass all the relays.

BE VERY CAREFUL!

Do not touch the manifold and body parts with the jumper (they are very close). Make sure the nut on the solenoid is tight and the jumper does not touch hot exhaust manifold. first connect the jumper to the solenoid THEN to the battery.

I have been driving with jumper for a year or so until I finally replaced the starter. Without th ejumpr it would not even click (bad solenoid I guess).

The saddest thing in life is wasted talent

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Yup, I can make it turn over using a simular method.... I just short a screwdriver between the "crank" connection on the solenoid and the hot batt cable on the solenoid. Learned that trick on a '69 camaro in high-school... the camaro had wiring issues.

The car turns over that way... but not by the key. The starter and solenoid are both new... no crank voltage to the solenoid from harness...

I traced the circuit back to where it goes into a thick loom with no voltage showing... Haynes manual is showing a "starter interrupt relay" but doesn't give any location. Another fellow mentioned the rocker panel on pass side... will also look there tomorrow....

This is what was left of the suburban..

IPB Image

This is myself (with hat), dad and brother...

IPB Image

mike

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Yup, I can make it turn over using a simular method.... I just short a screwdriver between the "crank" connection on the solenoid and the hot batt cable on the solenoid. Learned that trick on a '69 camaro in high-school... the camaro had wiring issues.

The car turns over that way... but not by the key. The starter and solenoid are both new... no crank voltage to the solenoid from harness...

I traced the circuit back to where it goes into a thick loom with no voltage showing... Haynes manual is showing a "starter interrupt relay" but doesn't give any location. Another fellow mentioned the rocker panel on pass side... will also look there tomorrow....

This is what was left of the suburban..

IPB Image

This is myself (with hat), dad and brother...

IPB Image

mike

I believe the relay is under the drivers side door sill panel, I am having the same issues with my 92 STS but the weather up here has been lousy the last few days and I have been unable to get back at mine. Uncletom

My condolences to you and your family for the loss of your father.

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Have you attempted to start the car while moving the shift lever? It is possible the newtral safety switch is bad. Unplug the newtral safety switch and make sure the contacts are not all corroded.

Once you get the proper wiring diagram, you should be able to pinpoint the problem. You could eliminate the VATS system by measuring the resistance of the ignition key pellet and then purchase a combination of resistors from Radio Shack in order to obtain the correct resistance. Unplug the VATS connector under the dash - the wire comes from inside the column and looks like a phone cord - the outer jacket is orange with two small, white wires iniside. Temporarily connect the resistor network to the vehicle side of the harness (not the ignition key side) and attempt to start the car. If it starts, you've found the problem.

I'd also check the starter interrupt relay - someone with a '91 shop manual is sure to post the diagram and location.

The problem could also be the ignition switch - it is buried in the column.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I have a 91 Seville/Eldo manual, will this help Kevin?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The problem could also be the ignition switch - it is buried in the column.

It's not that deep, Kevin. It's attached to the bottom of the column, no need to diassemble the latter. But probably the column should be lowered which is not a big deal.

The saddest thing in life is wasted talent

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starter enable relay for 92 deville is behind glovebox above bcm :)

Great!! Now I have a location... problem is there are about 9 relays on that sub-panel. Can you tell me if it is the one hanging loose by the wiring (rectangular rather than square like the rest of them).. or which one of the 7 or 8 on the panel?

I drove to Fort Worth yesterday to file insurance claims for my dad and got side-tracked... so didn't even get a chance to look at the caddy. A buddy is stuffing a 420 ci small-block stroker in his Camaro and had questions about valvetrain geometry... so I made a sidetrip.

IPB Image

The one coming out is a 383... pretty frickin' hot motor itsself... come over and check us out on nasty z-28 page... lots of good folks over there too!!

Will try to get back at it today sometime, and will report any findings....

Thanks guys...

mike

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Have you attempted to start the car while moving the shift lever? It is possible the newtral safety switch is bad. Unplug the newtral safety switch and make sure the contacts are not all corroded.

Once you get the proper wiring diagram, you should be able to pinpoint the problem. You could eliminate the VATS system by measuring the resistance of the ignition key pellet and then purchase a combination of resistors from Radio Shack in order to obtain the correct resistance. Unplug the VATS connector under the dash - the wire comes from inside the column and looks like a phone cord - the outer jacket is orange with two small, white wires iniside. Temporarily connect the resistor network to the vehicle side of the harness (not the ignition key side) and attempt to start the car. If it starts, you've found the problem.

I'd also check the starter interrupt relay - someone with a '91 shop manual is sure to post the diagram and location.

The problem could also be the ignition switch - it is buried in the column.

Yup, I tried wiggling it in park and neutral... nothing to the input of the safety switch as far as a cranking signal... I figure it is upstream of there, which is why I was looking for the interrupt relay.

The key pellet measured zero ohms on both keys.. so jumping the VATS circuit should be a breeze if it comes to that. One of the keys has been a spare... so I trust it's reading.

Thanks,

mike

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Have you attempted to start the car while moving the shift lever? It is possible the newtral safety switch is bad. Unplug the newtral safety switch and make sure the contacts are not all corroded.

Once you get the proper wiring diagram, you should be able to pinpoint the problem. You could eliminate the VATS system by measuring the resistance of the ignition key pellet and then purchase a combination of resistors from Radio Shack in order to obtain the correct resistance. Unplug the VATS connector under the dash - the wire comes from inside the column and looks like a phone cord - the outer jacket is orange with two small, white wires iniside. Temporarily connect the resistor network to the vehicle side of the harness (not the ignition key side) and attempt to start the car. If it starts, you've found the problem.

I'd also check the starter interrupt relay - someone with a '91 shop manual is sure to post the diagram and location.

The problem could also be the ignition switch - it is buried in the column.

The key pellet measured zero ohms on both keys.. so jumping the VATS circuit should be a breeze if it comes to that. One of the keys has been a spare... so I trust it's reading.

Thanks,

mike

Zero?? :blink:

The saddest thing in life is wasted talent

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Seems hard to believe that the key pellet could be ZERO on both keys, check your ohms scale on your ohm meter to be sure...

Doesn't the 91 display a STARTER DISABLED message on the DIC if there is a problem?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Seems hard to believe that the key pellet could be ZERO on both keys, check your ohms scale on your ohm meter to be sure...

Doesn't the 91 display a STARTER DISABLED message on the DIC if there is a problem?

You are correct Mike. It would show the message. Something like"wait 3 minutes".

The saddest thing in life is wasted talent

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Have you attempted to start the car while moving the shift lever? It is possible the newtral safety switch is bad. Unplug the newtral safety switch and make sure the contacts are not all corroded.

Once you get the proper wiring diagram, you should be able to pinpoint the problem. You could eliminate the VATS system by measuring the resistance of the ignition key pellet and then purchase a combination of resistors from Radio Shack in order to obtain the correct resistance. Unplug the VATS connector under the dash - the wire comes from inside the column and looks like a phone cord - the outer jacket is orange with two small, white wires iniside. Temporarily connect the resistor network to the vehicle side of the harness (not the ignition key side) and attempt to start the car. If it starts, you've found the problem.

I'd also check the starter interrupt relay - someone with a '91 shop manual is sure to post the diagram and location.

The problem could also be the ignition switch - it is buried in the column.

Yup, I tried wiggling it in park and neutral... nothing to the input of the safety switch as far as a cranking signal... I figure it is upstream of there, which is why I was looking for the interrupt relay.

The key pellet measured zero ohms on both keys.. so jumping the VATS circuit should be a breeze if it comes to that. One of the keys has been a spare... so I trust it's reading.

Thanks,

mike

None of the pellets are zero ohms - make sure the meter leads only touch the metal contacts that are imbedded in the plastic pellet. If the pellet measures zero ohms, that is the problem. A Cadillac parts counter can run your VIN and test the ignition key.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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