1994 Jaguar XJS 94 XJS L6 4:liter engine no start (No Spark

JAGMAN64

MEMBER
1994 JAGUAR XJS
6 CYL
2WD
AUTOMATIC
53,000 MILES

Before I had complete no start, I checked voltage at ignition coil and it only had 8 volts at positive and negative terminals. Engine seemed to start only after you released key, not while cranking.I pulled fuse from engine management control and still have low voltage at ignition key circuit. Jumped ignition key connection and still have low voltage. Ignition key circuit has about 5 connections to the instrument pack.I was wondering if one of the gauges in the instrument pack could be pulling the voltage down.I was thinking of disconecting the ground wire for the instrument pack and see if battery voltage is obtained. Does this sound feasible?Is it posible that the 94 Jag. L6 4:0 liter engine doesn`t requirer 12 volt key voltage for engine management?I hope one of you guys out there can help me.

7 Replies

DAVE H

MECHANIC
13,383 POSTS

Have you checked the voltage at battery terminals?

Was this

answer

helpful?

Yes

Friday, February 26th, 2010 AT 7:08 PM

JAGMAN64

MEMBER
6 POSTS

Hi Dave, I checked battery and it is good.I have low voltage (8 volts) going to engine management system. The ignition coil is only getting 8 volts also.I`M pretty sure it requirers 12 volts to operate engine management system. Starter turns engine over good. Hope your able to give me some help with this problem. Thanks, HarryK

SPONSORED LINKS

Was this

answer

helpful?

Yes

Sunday, March 7th, 2010 AT 5:48 AM

DAVE H

MECHANIC
13,383 POSTS

Which pins/colored wires are you checking voltage on @ PCM ?? there should be 12v .. please check again you have 12v across battery terminals or replace the battery ...also check the EMS main relay is good !!

let me know

Was this

answer

helpful?

Yes

Monday, March 8th, 2010 AT 5:23 AM

JAGMAN64

MEMBER
6 POSTS

Dave, the ems main relay has 12 volts coming in from another circuit. The ignition circuit that turns the ems relay on only has 8 volts.I pulled the fuse that protects the pcm circuit (ems) and it still has only 8 volts. Voltage loss is from ignition key to fuse holder. When I turn engine over, rpm gauge does`nt move till key is released.I believe this happens because of the low voltage going to ignition amplifier and ignition coil.

Was this

answer

helpful?

Yes

Monday, March 8th, 2010 AT 9:01 AM

DAVE H

MECHANIC
13,383 POSTS

Hey.

I need you to check/replace the Auxiliary Ignition Load Relay On right component panel. See Fig. 1

let me know

SPONSORED LINKS

Was this

answer

helpful?

Yes

Wednesday, March 10th, 2010 AT 4:12 AM

JAGMAN64

MEMBER
6 POSTS

Dave, I have already checked out the main & aux. Load relays. They are good and I even substituded other relays for them. Ignition switch position one, 12 volts flow through ignition circuit. Position 2 only 8 volts.I pulled fuses one by one and voltage did not increase in ignition circuit.I bought this car in November and I beleive some of the gauges have been replaced. The battery condition gauge did not fuction right. Is it possible the problem could be in the instrument pack?

Was this

answer

helpful?

Yes

Wednesday, March 10th, 2010 AT 5:15 AM

JAGMAN64

MEMBER
6 POSTS

Found problem, ignition power feed wire from bulk head not making good contact. The power lead is located inside car behind dash on bulkhead (firewall). Connection felt tight but when you applied pressure to it battery voltage stayed up when ignition key was moved to position 1 or 2. Just tighten wire connection nut. HarryK

Was this

answer

helpful?

Yes

-1

Sunday, November 20th, 2011 AT 12:08 PM