Ford heated windshield system

[junkyardjeff]

I have a 89 crown vic with a heated windshield and with other electrical accessories on while the heated windshield is on the voltage drops to 11.6 volts,I always suspected the voltage regulator but I did some checking with the lights on and off I noticed the regulator stepped up the voltage with other accessories on but it wont keep up with the heated windshield on. Unfortunately the windshield and rear window defroster can not be operated seperately but the rear window does not seem to be drawing too much voltage after the windshield turns off,is there anything I can do to to improve the situation or just wait until the windshield turns off before driving.

[wayne petty]

jeff run this...  its easy..

i have had terrible issues with ford ground wires fatiguing..  and dirty...

since electrons flow from negative to positive... if you don't have a good ground.. you will not have a enough to operate the device..

you may also want to take apart the positive battery connections at the solenoid on the inner fender and wire brush both sides...






this might be what most of the solenoid wiring is..



this is an improper way to connect a ground wire between the engine and the firewall..  not saying that yours is improperly grounded..




this jeep had a disconnected battery cable at the side of the block.. i got it started by using jumper cables from the negative battery to the engine block..



you could hook up one jumper from the negative battery to the engine block and the other from the negative battery to the body ... and see if your electronics start working..

sorry to bury you in info...

print the voltage drop test and run it..

post results by number

1......

2.....

3....

4.....

[junkyardjeff]

Whiles I was tinkering with it today I cleaned the body to battery ground along with the headlight grounds,I also made a ground cable to go from the regulator to the body since it sitting on a plastic inner fender. I will have to look for my wiring diagram and see where the windshield heater grounds. I had all that wiring apart since I had to replace the front clip but that was a couple years ago,I am also wondering if the windshield could be going bad and causing for resistance.  It also looks to have the original voltage regulator too,it does bump up the voltage for everything else except for the windshield heater.

[wayne petty]

engine off...

use your thumb on the alternator fan blade.. see if there is enough belt tension...

i have had a LOT of issues with belt tensioners lately..

i had one just recently that as the belt wore the tensioner had lived at that spot so long it would not take up the slack and the 8 horse power the alternator needed to spin was not transfered.. even though the belt was not squealing..

[UGLY OLDS]

Hey Jeff ...
Crazy Question  .. Did that car ever have 2 alternators  I remember Ford heated windshields running on 110 volts with a completely dedicated system in the past ... As I remember , all the dedicated wiring was an "odd" color & labeled as "High Voltage" or something .... Maybe it was earlier years .... :?

 Maybe that info fell out along the line to allow some new info in ... With us old guys thats the way it works ...Old info must leave before new info can be absorbed ....  



Bob ....

[junkyardjeff]

It only has one alternator and it looks a little larger then the normal Ford alternator,after the motor is running for a few minutes the voltage is around 14.25 and goes up to 14.35 with the lights and fan motor on. With just the rear defroster on its at 14.35 but when the lights,fan and both the windshield and rear defroster on it goes below 12 volts,the windshield only stays on about 10 minutes and the idle will go up when its on but it really draws the power down.

[wayne petty]

jeff... i have an 89 CV shop manual... section 43 is the fixed glass section...

the heated windshield covers 10 pages..

drop me a PM with your direct email address and i will scan the pages... if you want...  


edit... this is the proper wiring diagram for the heated windshield...

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/1e/4c/28/large/0900c152801e4c28.gif


found this online..

The heated windshield was achieved with a gold (real gold) metal film between the layers of glass. It made the whole entire windshield electrically heated

The heated windsheild requires an externally regulated alternator, relays and control box (and related wiring to hook it all up). When you hit the switch, it removes the alternator from the cars electrical system, full fields the alternaotr and applies the alternator output to the windshield (timed output, along with temperature sensing, any windsheild cracks will make the system inop).
Your car runs ON BATTERY only while the heated windshield is doing its thing. Not something I personally like, as the battery needs all the help it can get to charge up after a cold start that would necessitate windshield heating.
Anyway, it also senses battery voltage, and if it drops below I think 9 volts (may be 10) it turns off the heated windshield and puts the alternator back into the main system.
Control box somewhere behind the glove box, relay and further controls behind the battery, something else somewhere along the firewall.

[junkyardjeff]

It looks like its working like it should and probably not be driven while its on,the problem is if you only want the rear window on both will come on unless the windshield is too warm to kick it on. It looks like ford should have stayed with the two alternator system for the heated windshield,I found out I have a shop manual and a wiring diagram so I am covered if I need to do any repairs. I have found out if the windshield ever gets broken replacements are not being made and it comes in handy for the snowy days we have here in Ohio in the winter,if not a dual alternator system dual batteries would help.