I've overheated in Fort Worth, and as I await the hook from AAA to haul me home, I've checked both 30A fuses in the left engine fuse box, F11 & F17; and found both have failed.


Looks like I have some troubleshooting to do.....

 

Bad (locked up) fan motors will blow the fuses!

 

Here are the TSBs I told you about when you called me.
Fans 'jumping' from NO FAN to HIGH SPEED may cause the fuses to blow due to abnormally high current draw.

The fans must transition from LOW to High to prevent this fault.

Read all three TSBs.

Make sure your car falls within the VIN range and has the Schrader valve before removing the pressure switch if you choose to do so or you must evacuate the system.

bob gauff

 

Thanks Ross, thanks Bob! I'll read thru them here in a minute..or perhaps tomorrow morning as it is getting late.


I was in the middle lane westbound on N. Tarrant Pkwy stuck in heavy stopped traffic just East of Denton Hwy for those who are familiar, when I noticed the temp guage pegged. I called up the parameters on my phone using the Torque App and it was showing coolant temp at 249. I had to endure two light cycles until I could get clear and off the road at the Aldi just West of Denton Hwy. Whilst waiting for the green to cross Denton, I began to get percolating noises and steam began wafting out of the left side bonnet-to-wing seam! I was at 257.5F by the time I got it shut down. I noted the percolating noises were coolant forcing its way past the pressure cap.


So after what seemed an eternity on hold with AAA, the dispatcher summed up, "Mr. Holbrook, it is 7:04 pm and something-or-another towing will be there by 7:34 pm. I have that you've agreed to text msg updating so you can expect updates periodically on the driver's location."


Alrighty then. In the interim, besides interrupting Bob's dinner, I found the fuses and confirmed both 30A's were blown, and confirmed I had spares in the on-board tool shed integrated to the right wing.


About 7:45 I texted AAA that I had yet to see any tow truck nor text msg location update and headed into Aldi to purchase a couple of gallons of "purified" water - they don't carry distilled. Returned to the car and topped up the overflow tank using about 7/8 of one gal. Replaced the two blown fuses with spares, made a last check of traffic on the phone, turned the key on and checked that I had the climate control "OFF" and confirmed coolant temp at 125F, cranked her up and departed the Aldi lot at 8:04 pm.


AAA called to ask if I'd seen the towing service about 8:10 and I informed her I'd grown impatient, effected a temporary fix and chosen to egress the metroplex. After a pregnant pause on the other end, I restated, "Nobody showed up, I fixed the car and left."


"Awww sir, I just called to tell you he's almost there and we're sorry for the delay it's just been crazy tonight. He should be calling you any minute to tell you he's almost there." (I'm still puzzled by her initial question as to whether or not I'd seen them if she was calling to tell me they'll be here presently?)


"Fine and dandy, but I'm no longer there, tell him not to bother calling and head back to the shop or next call, I won't be conducting any business with him this evening..."


There were 7 stoplights between me and the freeway and I got caught at 3 of them. I kept climate control off the entire time after Bob advised that there could be a failed switch for the low-speed fans and climate-control may be trying to command the fans from Off straight to high which would blow the fuses. Temp never got above 195 and maintained 185 once I gained the freeway.


When I got home, I popped the bonnet and let it idle, neither fan was running - I let the temp climb to 202 and fans still didn't come on. Replacement fuses are not yet blown. (I do not have the wire loop mod that brings the fans on "Low" anytime the key is on)


I'm 737551, so allegedly I have Schrader valves! Yay!

 

After performing the diagnoses in 14-04; I've mended it in accordance with 14-06. Thanks again for posting those, Bob!

 

Wow, that was quick work to get it fixed. Where did you get the modification kit so fast?


Are you planning to dump the coolant and refill?

 

The connector is part of the failed switch assembly. It has about an 8" pigtail from the switch to the connector, with all but about a half-inch covered by a fabric-like sleeve, loose fitting, not quite plastic, not quite cloth.


Firstly, the switch has failed and is no longer of any use. However, the pigtail has some value. I just slid the sleeve back as far as I could from where the leads come out of the switch and snipped both wires with a pair of dykes. Now you can carry the connector and pigtail round to your workbench, or even down to the house and work at your desk, if you like....and slide the sleeve off...do whatever or however you roll. I cut the wires in a staggered fashion because that's how I usually roll, and because I haven't sharpened my thinker in awhile. Usually stagger such an arrangement so I don't have to fit two splices side-by-side and make a larger bundle. Anyway....I quickly realized what was called for here was an even cut, strip, and twist the two wires together as if I were going to secure them with a wire nut.


So I removed the sleeve, snipped the long wire off even with it's buddy, slid a couple of pieces of shrink tube over the wires down near the connector, then stripped about 3/8" of the insulation from both. Dipped 'em in flux, twisted 'em together and soldered them up tight. (a wire nut would've worked just fine, I was going for weatherproof.) After soldering the ends, I put a piece of heat-shrink over the joint leaving about 1/2" free overhang. Hit it with the heat gun. After it cooled, I folded the free end of the shrunken heat-shrink back down over the wire and slipped another piece of heat-shrink over that, sealing out a moisture path. Then I shrunk a piece of wrap around the wires down at the back of the connector just to keep things tight and tidy. Next, I slipped the original sleeve over the whole mess and it was now longer than the pigtail. I shrunk a wrap around it at the connector just to help hold it in place, then did the same fold/heat-shrink/fold/heat-shrink trick at the free end. Cinched it down to the wires with a tiny zip tie because the sleeve would still slide off the wires if you pulled on it fairly aggressively.


Then, re-installed the harness-side of the connector to its keeper, plugged in the pigtail, and tied off the free end to the cut leads coming from the failed pressure switch. It is the wire coming from the white connector with the orange zip-tie on it:



There are other ways:
1) use one of those hateful little blue crimp-splices on the two wires anywhere between the switch and the connector





2) search high and low for the Genuine Jaguar Cars ltd kit
JLM 12453 with a "harness shorting plug" and then sit on the front porch til it shows up and you are some $30-$40 lighter....


No plans to renew the coolant. I put in fresh Zerex G-05 long life coolant about a year and half and less than 40k miles ago. It took about 7/8 of a gallon of water to top up Aldi, and this morning when everything was cool I added probably a quart or more of full-strength Zerex to bring it back to topping. I'll have to flush my heater core with water again before winter sets in, and will top up that evolution with pure instead of 50/50; then check it with a hygrometer for a warm fuzzy, but I was maybe a little beyond 50/50, heavy on anti-freeze light on water anyway. I'm more concerned with the condition of the oil than the coolant after cooking, I'll do the next oil change soon...and ahead of normal schedule.

 

I went out and checked my car and I must have the harness shorting plug.

 

Yes you do! And the special cap in lieu of a failed switch. Even so by VIN I should have the Schrader. I see no value in removing the switch unless/until it starts leaking.


But your initial bewilderment at my speed was understandable..... not likely to get all those parts in-hand and installed within a few hours of diagnosing the failure. When I said, "IAW TSB 14-06" I meant spirit vice "letter."

 

I've been a member for a few years now but have not had a reason to post in quite some time...until now.
I have a 1995 VDP and more recently obtained a local 1997 VDP. I noticed in the 1997 the cooling fans would come on before even starting. My 1995 does not do this. I dismissed the thought, and had forgotten about it until seeing this post the other day. I looked at the service bulletins and checked both of my cars and sure enough the 97 has only the one switch and the shorting plug, the 95 had both pressure switches. My fans have not failed but knowing that this is a tendency I've decided to go ahead and perform the modification. A guy I've bought a handful of parts from on eBay in the last 2 years was able to supply me with the shorting plug, which I installed and have removed the pressure switch. It unscrewed and came off with a loud little pop of pressure release. It's not leaking so the Schrader valve is still good. Now I just need to hunt down that specific valve cap!!