1989 Volkswagen Jetta No spark

MAMBROZ

MEMBER
1989 VOLKSWAGEN JETTA
4 CYL
FWD
MANUAL
112,000 MILES

So here's what I'm havin troubles with. I'm getting no spark to the plugs. I have tested the hall sender, the ignition control module (ICM), the coil, knock sensor, coolent sensors, and the afm. As well as replaced plugs and new spark wires. When I test the coil with the key on I get 12volts to it. I did test the four individual wires ( 2 red/black for neg and 2 black for pos) 1 r/b gets full 12v and one does not same with the black wires. I read that I needed to have a heavier ground to the coil mount so I have done that as well. All grounds are free of corosion as well as connected. I have also bypassed the ign switch was told that may be a prob as well. At this point I have replaced the complete ign system and still have no spark. I do not have a clue of wat else to do. Could this be an ECU prob?

1 Reply

KHLOW2008

MECHANIC
41,815 POSTS

Hi Mambroz,

Thank you for the donation.

For the older models, the ECU does not control the sparking as a distributor and Ignition control Unit is used. From the symptom description, I believe the most likely cause is the ICM. You mentioned replacing the ICM, was it new or used?

Here are the diagnostic procedures, hope it is helpful.

Ignition Control Unit.

1. Perform SPARK check. If secondary spark is present, ignition control unit is okay. If not, turn ignition off. Disconnect ignition control unit wire harness connector. Turn ignition on. Using a voltmeter, measure voltage between terminal No. 2 (-) and terminal No. 4 (+) of connector. See Fig. 6 .

2. Voltage should be present. If not, ensure continuity exists between terminal No. 2 and ground. Continuity must also exist between terminal No. 4 and ignition coil positive terminal. Repair wiring if necessary. If wiring is okay, replace ignition control unit.